Develop Reference

Can't build apk in release version

When I deploy apk in debug version there is no warning, but when I try to build apk in release version I got this warning, please anybody help.
Warning:com.jjf2017.activity.MainActivity$43$$Lambda$1: can't find referenced class java.lang.invoke.LambdaForm$Hidden
Warning:com.jjf2017.fragment.ArtistIDFragment$$Lambda$1: can't find referenced class java.lang.invoke.LambdaForm$Hidden
Warning:com.jjf2017.fragment.ArtistIDFragment$$Lambda$2: can't find referenced class java.lang.invoke.LambdaForm$Hidden
Warning:com.jjf2017.fragment.ArtistINFragment$$Lambda$1: can't find referenced class java.lang.invoke.LambdaForm$Hidden
Warning:com.jjf2017.fragment.ArtistINFragment$$Lambda$2: can't find referenced class java.lang.invoke.LambdaForm$Hidden
Warning:com.jjf2017.fragment.CcFragment$$Lambda$1: can't find referenced class java.lang.invoke.LambdaForm$Hidden
Warning:com.jjf2017.fragment.TicketFragment$$Lambda$1: can't find referenced class java.lang.invoke.LambdaForm$Hidden
Warning:org.joda.time.DateMidnight: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.DateTime: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.DateTimeZone: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.DateTimeZone: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Days: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Days: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Duration: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Hours: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Hours: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Instant: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.LocalDate: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.LocalDate: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.LocalDateTime: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.LocalDateTime: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.LocalTime: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.LocalTime: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Minutes: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Minutes: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.MonthDay: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.MonthDay: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Months: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Months: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.MutableDateTime: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.MutablePeriod: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Period: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Seconds: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Seconds: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Weeks: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Weeks: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.YearMonth: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.YearMonth: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Years: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Years: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.base.AbstractDateTime: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.base.AbstractDuration: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.base.AbstractInstant: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.base.AbstractPeriod: can't find referenced class org.joda.convert.ToString
Warning:retrofit2.Platform$Java8: can't find referenced class java.lang.invoke.MethodHandles$Lookup
Warning:retrofit2.Platform$Java8: can't find referenced class java.lang.invoke.MethodHandle
Warning:retrofit2.Platform$Java8: can't find referenced class java.lang.invoke.MethodHandles
Warning:retrofit2.Platform$Java8: can't find referenced class java.lang.invoke.MethodHandle
Warning:retrofit2.Platform$Java8: can't find referenced class java.lang.invoke.MethodHandles$Lookup
Warning:retrofit2.Platform$Java8: can't find referenced class org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement
Warning:there were 52 unresolved references to classes or interfaces.
Warning:Exception while processing task java.io.IOException: Please correct the above warnings first.
Error:Execution failed for task ':app:transformClassesAndResourcesWithProguardForRelease'.
Job failed, see logs for details

Error:Execution failed for task ':app:transformClassesAndResourcesWithProguardForRelease' means that
you're using proguard in release.
Try to set minifyEnabled option in your build.gradle file to false.
Like this:
buildTypes {
release {
minifyEnabled false
...
}
}

if your app still working when you make
minifyEnabled false
then you have to dontwarn manually every warning that you have with -dontwarn
Exempel: -dontwarn java.lang.invoke.**

Android Proguard "Can't find referenced"

I want to generate a signed apk. But I reached the 64k methods limit so I searched for some solutions and one of them is to use proguard.
I edited my build.gradle like this:
buildTypes {
release {
minifyEnabled true
shrinkResources true
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
When I then try to generate the signed apk I get a lot of warnings:
Warning:com.akexorcist.roundcornerprogressbar.TextRoundCornerProgressBar$2: can't find referenced method 'android.widget.TextView access$000(com.akexorcist.roundcornerprogressbar.TextRoundCornerProgressBar)' in program class com.akexorcist.roundcornerprogressbar.TextRoundCornerProgressBar
Warning:com.akexorcist.roundcornerprogressbar.TextRoundCornerProgressBar$2: can't find enclosing method 'void setTextProgressAlign()' in program class com.akexorcist.roundcornerprogressbar.TextRoundCornerProgressBar
Warning:com.github.mikephil.charting.data.realm.base.RealmBarLineScatterCandleBubbleDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.base.RealmBarLineScatterCandleBubbleDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmBaseDataSet: can't find referenced class io.realm.Sort
Warning:com.github.mikephil.charting.data.realm.base.RealmBaseDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.base.RealmBaseDataSet: can't find referenced class io.realm.Sort
Warning:com.github.mikephil.charting.data.realm.base.RealmBaseDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.base.RealmBaseDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmLineRadarDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.base.RealmLineRadarDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmLineRadarDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmLineRadarDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.base.RealmLineRadarDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmLineRadarDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmLineRadarDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmLineRadarDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmLineRadarDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.base.RealmLineRadarDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmLineScatterCandleRadarDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.base.RealmLineScatterCandleRadarDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmUtils: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.base.RealmUtils: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmUtils: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmUtils: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.base.RealmUtils: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmUtils: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmUtils: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.base.RealmUtils: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.base.RealmUtils: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.base.RealmUtils: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmList
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmList
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmList
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmList
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmList
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBarDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmBubbleDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmCandleDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmLineData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmLineData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmLineData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmLineData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmLineDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmLineDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmPieDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmRadarData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmRadarData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmRadarData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmRadarData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmRadarDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmRadarDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterData: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterData: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterDataSet: can't find referenced class io.realm.DynamicRealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterDataSet: can't find referenced class io.realm.RealmObject
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterDataSet: can't find referenced class io.realm.RealmResults
Warning:com.github.mikephil.charting.data.realm.implementation.RealmScatterDataSet: can't find referenced class io.realm.RealmObject
Warning:there were 283 unresolved references to classes or interfaces.
Warning:there were 2 unresolved references to program class members.
Warning:Exception while processing task java.io.IOException: Please correct the above warnings first.
Error:Execution failed for task ':app:transformClassesAndResourcesWithProguardForFreeRelease'.
> java.io.IOException: Please correct the above warnings first.
So the problem seem to be the repositories I implemented. I read that I have to configurate the proguard-rules.pro file but I never used this before and have no idea about the syntax.
How can I fix that?
EDIT
Dependencies:
compile fileTree(include: ['*.jar'], dir: 'libs')
compile 'com.android.support:appcompat-v7:24.2.1'
compile 'com.android.support:design:24.2.1'
compile 'com.android.support:recyclerview-v7:24.2.1'
compile 'com.android.support:cardview-v7:24.2.1'
compile 'com.bignerdranch.android:expandablerecyclerview:2.1.1'
compile 'com.github.lzyzsd:circleprogress:1.1.0#aar'
compile 'com.github.PhilJay:MPAndroidChart:v2.2.3'
compile 'net.qiujuer.genius:ui:1.5.2'
compile 'com.akexorcist:RoundCornerProgressBar:2.0.3'
compile 'com.rengwuxian.materialedittext:library:2.1.4'
compile 'com.github.medyo:fancybuttons:1.8.1'
compile 'com.google.android.gms:play-services:9.6.1'
compile 'com.github.sundeepk:compact-calendar-view:1.9.3'

There are two problematic libraries:
RoundCornerProgressBar
MPAndroidChart
The first problem is with the class com.akexorcist.roundcornerprogressbar.TextRoundCornerProgressBar. There is a solution here that overcomes the problem, by adding to Proguard:
-dontwarn com.akexorcist.roundcornerprogressbar.TextRoundCornerProgressBar
The second one is simply solved by adding two statements to Proguard that the author of the library clearly describes here:
-keep class com.github.mikephil.charting.** { *; }
-dontwarn io.realm.**
Your Proguard file should contain those lines and the problems should disappear.

buildTypes {
release {
debuggable false
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
debug {
debuggable true
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}

app:transformClassesAndResourcesWithProguardForRelease

Error:Execution failed for task
':app:transformClassesAndResourcesWithProguardForRelease'.
java.io.IOException: Please correct the above warnings first.
I have tried my best to find the solution but I did not get, whereas I found many questions.
Is there anything to ignore these warnings, I just want to generate a secure signed apk, therefore I have used minifyEnabled true
Message:
Warning:retrofit.client.OkClient$1: can't find superclass or interface com.squareup.okhttp.RequestBody
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.OkHttpClient
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Cache
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.OkHttpClient
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.CacheControl
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.CacheControl$Builder
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Request$Builder
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.OkHttpClient
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Call
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Response
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.ResponseBody
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Response
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.ResponseBody
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.OkHttpClient
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Cache
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.CacheControl
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.CacheControl$Builder
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Request$Builder
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Response
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Cache
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.CacheControl
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Request
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Call
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Response
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.ResponseBody
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.OkHttpClient
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.CacheControl$Builder
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.CacheControl
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Request$Builder
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Response
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.ResponseBody
Warning:com.squareup.picasso.OkHttpDownloader: can't find referenced class com.squareup.okhttp.Cache
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPMethod
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.URLFetchServiceFactory
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.URLFetchService
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPRequest
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPHeader
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPRequest
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPResponse
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPRequest
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPResponse
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPHeader
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPResponse
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPMethod
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPRequest
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPResponse
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPHeader
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPMethod
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.URLFetchServiceFactory
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.URLFetchService
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPResponse
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.URLFetchService
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPMethod
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.URLFetchService
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPRequest
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPResponse
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.URLFetchService
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPRequest
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPResponse
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.URLFetchService
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPRequest
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPMethod
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPRequest
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPResponse
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPRequest
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPHeader
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPResponse
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPRequest
Warning:retrofit.appengine.UrlFetchClient: can't find referenced class com.google.appengine.api.urlfetch.HTTPHeader
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.OkHttpClient
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Call
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Request$Builder
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Response
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Request
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Response
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.MediaType
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.ResponseBody
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Headers
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.OkHttpClient
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Request$Builder
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Call
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Request
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Response
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.MediaType
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.ResponseBody
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Headers
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.OkHttpClient
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Request
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Request$Builder
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Response
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.RequestBody
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.MediaType
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.ResponseBody
Warning:retrofit.client.OkClient: can't find referenced class com.squareup.okhttp.Headers
Warning:retrofit.client.OkClient$1: can't find referenced class com.squareup.okhttp.RequestBody
Warning:retrofit.client.OkClient$1: can't find referenced class okio.BufferedSink
Warning:retrofit.client.OkClient$1: can't find referenced class com.squareup.okhttp.RequestBody
Warning:retrofit.client.OkClient$1: can't find referenced class okio.BufferedSink
Warning:retrofit.client.OkClient$1: can't find referenced class com.squareup.okhttp.MediaType
Warning:retrofit.client.OkClient$1: can't find referenced class okio.BufferedSink
Warning:retrofit.client.OkClient$2: can't find referenced class com.squareup.okhttp.ResponseBody
Warning:retrofit.client.OkClient$2: can't find referenced class com.squareup.okhttp.MediaType
Warning:retrofit.client.OkClient$2: can't find referenced class com.squareup.okhttp.ResponseBody
Warning:retrofit.client.OkClient$2: can't find referenced class com.squareup.okhttp.MediaType
Warning:retrofit.client.OkClient$2: can't find referenced class com.squareup.okhttp.ResponseBody
Warning:retrofit.client.OkClient$2: can't find referenced class com.squareup.okhttp.MediaType
Warning:retrofit.client.OkClient$2: can't find referenced class com.squareup.okhttp.ResponseBody
Warning:retrofit.client.OkClient$2: can't find referenced class com.squareup.okhttp.MediaType
Warning:rx.internal.util.unsafe.ConcurrentCircularArrayQueue: can't find referenced class sun.misc.Unsafe
Warning:rx.internal.util.unsafe.ConcurrentSequencedCircularArrayQueue: can't find referenced class sun.misc.Unsafe
Warning:rx.internal.util.unsafe.MpmcArrayQueueConsumerField: can't find referenced class sun.misc.Unsafe
Warning:rx.internal.util.unsafe.MpmcArrayQueueProducerField: can't find referenced class sun.misc.Unsafe
Warning:rx.internal.util.unsafe.SpmcArrayQueueConsumerField: can't find referenced class sun.misc.Unsafe
Warning:rx.internal.util.unsafe.SpmcArrayQueueProducerField: can't find referenced class sun.misc.Unsafe
Warning:rx.internal.util.unsafe.SpscArrayQueueConsumerField: can't find referenced class sun.misc.Unsafe
Warning:rx.internal.util.unsafe.SpscArrayQueueProducerFields: can't find referenced class sun.misc.Unsafe
Warning:rx.internal.util.unsafe.UnsafeAccess: can't find referenced class sun.misc.Unsafe

When you use ProGuard you have to always resolve all warnings to be able to process further with the build.
These warnings tell you that the libraries reference some code and there are no sources for that. That might and might not be ok. It depends if the problematic code ever get called.
In this case the libraries reference some code but the code doesn't seem to be ever called (e.g. because you didn't add some other library). In that case add -dontwarn rules to proguard-rules.pro file.
You use Retrofit and Picasso libraries. Try adding these rules:
-dontwarn okio.**
-dontwarn retrofit.**
-keep class retrofit.** { *; }
-keepclassmembers,allowobfuscation interface * {
#retrofit.http.** <methods>;
}
-dontwarn com.squareup.okhttp.**
It might fix your problem.
Note that you might experience further problems in runtime especially if any of those libraries use reflection and the code was shrunk and/or obfuscated. Then it's probable that you'll need more ProGuard rules for other libraries.
Edit:
To resolve RxJava related warnings add this dependency:
// ProGuard rules for RxJava
compile 'com.artemzin.rxjava:proguard-rules:1.1.1.0'
It adds necessary ProGuard rules for RxJava.

I had the same issue, and solved it by adding the following text to proguard-project.txt:
# for transformClassesAndResourcesWithProguardForRelease
# -- Picasso --
-dontwarn com.squareup.picasso.**
# -- OkHttp --
-dontwarn com.squareup.okhttp.internal.**
# -- Apache Commons --
-dontwarn org.apache.commons.logging.**
-ignorewarnings
-keep class *
{
public private *;
}

Android Volley Signed Apk Issue

I am working with an application where I am using volley plus with android studio. I am using volley plus gradle version 'dev.dworks.libs:volleyplus:+' gradle. When I make signed apk of my app my build process terminated with some warning and errors with runProguard true. There is any solution to solve this.
Warning:com.android.volley.toolbox.HttpClientStack$HttpPatch: can't find superclass or interface org.apache.http.client.methods.HttpEntityEnclosingRequestBase
Warning:com.android.volley.toolbox.multipart.MultipartEntity: can't find superclass or interface org.apache.http.entity.AbstractHttpEntity
Warning:com.android.volley.cache.SimpleImageLoader: can't find referenced class android.net.http.AndroidHttpClient
Warning:com.android.volley.cache.plus.SimpleImageLoader: can't find referenced class android.net.http.AndroidHttpClient
Warning:com.android.volley.misc.MultipartUtils: can't find referenced class org.apache.http.util.EncodingUtils
Warning:com.android.volley.misc.Utils: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.misc.Utils: can't find referenced class org.apache.http.Header
Warning:com.android.volley.misc.Utils: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.misc.Utils: can't find referenced class org.apache.http.Header
Warning:com.android.volley.misc.Utils: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.misc.Utils: can't find referenced class org.apache.http.Header
Warning:com.android.volley.misc.Utils: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.StatusLine
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.impl.cookie.DateUtils
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.HttpEntity
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.Header
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.StatusLine
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.HttpEntity
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.StatusLine
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.impl.cookie.DateUtils
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.HttpEntity
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.Header
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.StatusLine
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.StatusLine
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.HttpEntity
Warning:com.android.volley.toolbox.BasicNetwork: can't find referenced class org.apache.http.Header
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpUriRequest
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.message.BasicNameValuePair
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpUriRequest
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.HttpClient
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpPost
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.entity.ByteArrayEntity
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpPost
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpGet
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpDelete
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpPut
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpHead
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpOptions
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpTrace
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpEntityEnclosingRequestBase
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpUriRequest
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.HttpClient
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpEntityEnclosingRequestBase
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.HttpClient
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpUriRequest
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.NameValuePair
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpUriRequest
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpUriRequest
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpPost
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.HttpEntity
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpPost
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpPut
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpUriRequest
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpEntityEnclosingRequestBase
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.HttpEntity
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpEntityEnclosingRequestBase
Warning:com.android.volley.toolbox.HttpClientStack: can't find referenced class org.apache.http.client.methods.HttpUriRequest
Warning:com.android.volley.toolbox.HttpClientStack$HttpPatch: can't find referenced class org.apache.http.client.methods.HttpEntityEnclosingRequestBase
Warning:com.android.volley.toolbox.HttpClientStack$HttpPatch: can't find referenced method 'void setURI(java.net.URI)' in program class com.android.volley.toolbox.HttpClientStack$HttpPatch
Warning:com.android.volley.toolbox.HttpClientStack$HttpPatch: can't find referenced class org.apache.http.client.methods.HttpEntityEnclosingRequestBase
Warning:com.android.volley.toolbox.HttpHeaderParser: can't find referenced class org.apache.http.impl.cookie.DateUtils
Warning:com.android.volley.toolbox.HttpHeaderParser: can't find referenced class org.apache.http.impl.cookie.DateParseException
Warning:com.android.volley.toolbox.HttpHeaderParser: can't find referenced class org.apache.http.impl.cookie.DateUtils
Warning:com.android.volley.toolbox.HttpHeaderParser: can't find referenced class org.apache.http.impl.cookie.DateParseException
Warning:com.android.volley.toolbox.HttpStack: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.ProtocolVersion
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.message.BasicStatusLine
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.message.BasicHttpResponse
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.message.BasicHeader
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.message.BasicHttpResponse
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.entity.BasicHttpEntity
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.ProtocolVersion
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.StatusLine
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.message.BasicHttpResponse
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.entity.BasicHttpEntity
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.Header
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.ProtocolVersion
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.StatusLine
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.message.BasicHttpResponse
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.HttpResponse
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.HttpEntity
Warning:com.android.volley.toolbox.HurlStack: can't find referenced class org.apache.http.entity.BasicHttpEntity
Warning:com.android.volley.toolbox.Volley: can't find referenced class android.net.http.AndroidHttpClient
Warning:com.android.volley.toolbox.VolleyTickle: can't find referenced class android.net.http.AndroidHttpClient
Warning:com.android.volley.toolbox.multipart.BasePart: can't find referenced class org.apache.http.util.ByteArrayBuffer
Warning:com.android.volley.toolbox.multipart.BasePart: can't find referenced class org.apache.http.util.EncodingUtils
Warning:com.android.volley.toolbox.multipart.BasePart: can't find referenced class org.apache.http.util.ByteArrayBuffer
Warning:com.android.volley.toolbox.multipart.BasePart: can't find referenced class org.apache.http.util.EncodingUtils
Warning:com.android.volley.toolbox.multipart.BasePart: can't find referenced class org.apache.http.util.ByteArrayBuffer
Warning:com.android.volley.toolbox.multipart.Boundary: can't find referenced class org.apache.http.util.EncodingUtils
Warning:com.android.volley.toolbox.multipart.MultipartEntity: can't find referenced class org.apache.http.entity.AbstractHttpEntity
Warning:com.android.volley.toolbox.multipart.MultipartEntity: can't find referenced method 'void setContentType(java.lang.String)' in program class com.android.volley.toolbox.multipart.MultipartEntity
Warning:com.android.volley.toolbox.multipart.MultipartEntity: can't find referenced class org.apache.http.entity.AbstractHttpEntity
Warning:com.android.volley.ui.PhotoView: can't find referenced method 'float sqrt(float)' in library class android.util.FloatMath
Warning:com.rey.material.drawable.ContactChipDrawable: can't find referenced method 'float ceil(float)' in library class android.util.FloatMath
Warning:com.rey.material.text.style.ContactChipSpan: can't find referenced method 'float ceil(float)' in library class android.util.FloatMath
Warning:there were 158 unresolved references to classes or interfaces.
You may need to add missing library jars or update their versions.
If your code works fine without the missing classes, you can suppress
the warnings with '-dontwarn' options.
(http://proguard.sourceforge.net/manual/troubleshooting.html#unresolvedclass)
Warning:there were 2 unresolved references to program class members.
Your input classes appear to be inconsistent.
You may need to recompile the code.
(http://proguard.sourceforge.net/manual/troubleshooting.html#unresolvedprogramclassmember)
Warning:there were 3 unresolved references to library class members.
You probably need to update the library versions.
(http://proguard.sourceforge.net/manual/troubleshooting.html#unresolvedlibraryclassmember)
:app:proguardRelease FAILED
Error:Execution failed for task ':app:proguardRelease'.
> java.io.IOException: Please correct the above warnings first.

Use this code in ProGuard:
-dontwarn org.apache.http.**
-dontwarn android.net.http.AndroidHttpClient
-dontwarn com.google.android.gms.**
-dontwarn com.android.volley.toolbox.**

Since android API 23 Apache HTTP Client is removed from Android:
https://developer.android.com/about/versions/marshmallow/android-6.0-changes.html#behavior-apache-http-client
But Volley still uses it, that's why there is warn about can't find referenced class
We can ignore these warns, because Volley is still compiled using API 22:
https://github.com/mcxiaoke/android-volley/blob/master/gradle.properties
Still should think about other better libray like OkHttp, which uses HttpURLConnection, if Volley doesn't update in the future.

Proguard in Android Studio: Running proguardRelease complains of unresolved references

I'm trying to use Proguard for my release in Android Studio.
I have the classic problem that everyone has which is the "Unresolved references to classes or interfaces".
Like I read everywhere, I tried to add -dontwarn command to the proguard-project.txt file but it doesn't change anything.
Maybe my setup just ignore the proguard-project.txt file? Everything seems ok but I'm new to Android Studio, gradle and proguard so maybe I'm missing something! Any help is appreciated.
Here are my files:
proguard-project.txt
-dontwarn org.apache.**
project.properties
proguard.config=${sdk.dir}/tools/proguard/proguard-android.txt:proguard-project.txt
# Project target.
target=android-15
android.library=false
Current warning I receive
Warning:org.apache.commons.compress.archivers.sevenz.Coders$1: can't find referenced class org.tukaani.xz.X86Options
Warning:org.apache.commons.compress.archivers.sevenz.Coders$1: can't find referenced class org.tukaani.xz.PowerPCOptions
Warning:org.apache.commons.compress.archivers.sevenz.Coders$1: can't find referenced class org.tukaani.xz.IA64Options
Warning:org.apache.commons.compress.archivers.sevenz.Coders$1: can't find referenced class org.tukaani.xz.ARMOptions
Warning:org.apache.commons.compress.archivers.sevenz.Coders$1: can't find referenced class org.tukaani.xz.ARMThumbOptions
Warning:org.apache.commons.compress.archivers.sevenz.Coders$1: can't find referenced class org.tukaani.xz.SPARCOptions
Warning:org.apache.commons.compress.archivers.sevenz.Coders$BCJDecoder: can't find referenced class org.tukaani.xz.FilterOptions
Warning:org.apache.commons.compress.archivers.sevenz.Coders$BCJDecoder: can't find referenced class org.tukaani.xz.FinishableWrapperOutputStream
Warning:org.apache.commons.compress.archivers.sevenz.Coders$BCJDecoder: can't find referenced class org.tukaani.xz.FilterOptions
Warning:org.apache.commons.compress.archivers.sevenz.Coders$BCJDecoder: can't find referenced class org.tukaani.xz.FinishableOutputStream
Warning:org.apache.commons.compress.archivers.sevenz.Coders$LZMADecoder: can't find referenced class org.tukaani.xz.LZMAInputStream
Warning:org.apache.commons.compress.archivers.sevenz.DeltaDecoder: can't find referenced class org.tukaani.xz.DeltaOptions
Warning:org.apache.commons.compress.archivers.sevenz.DeltaDecoder: can't find referenced class org.tukaani.xz.FinishableWrapperOutputStream
Warning:org.apache.commons.compress.archivers.sevenz.DeltaDecoder: can't find referenced class org.tukaani.xz.DeltaOptions
Warning:org.apache.commons.compress.archivers.sevenz.DeltaDecoder: can't find referenced class org.tukaani.xz.UnsupportedOptionsException
Warning:org.apache.commons.compress.archivers.sevenz.LZMA2Decoder: can't find referenced class org.tukaani.xz.LZMA2Options
Warning:org.apache.commons.compress.archivers.sevenz.LZMA2Decoder: can't find referenced class org.tukaani.xz.LZMA2InputStream
Warning:org.apache.commons.compress.archivers.sevenz.LZMA2Decoder: can't find referenced class org.tukaani.xz.FinishableWrapperOutputStream
Warning:org.apache.commons.compress.archivers.sevenz.LZMA2Decoder: can't find referenced class org.tukaani.xz.LZMA2Options
Warning:org.apache.commons.compress.archivers.sevenz.LZMA2Decoder: can't find referenced class org.tukaani.xz.FinishableOutputStream
Warning:org.apache.commons.compress.archivers.sevenz.LZMA2Decoder: can't find referenced class org.tukaani.xz.LZMA2Options
Warning:org.apache.commons.compress.compressors.lzma.LZMACompressorInputStream: can't find referenced class org.tukaani.xz.LZMAInputStream
Warning:org.apache.commons.compress.compressors.xz.XZCompressorInputStream: can't find referenced class org.tukaani.xz.XZ
Warning:org.apache.commons.compress.compressors.xz.XZCompressorInputStream: can't find referenced class org.tukaani.xz.XZInputStream
Warning:org.apache.commons.compress.compressors.xz.XZCompressorInputStream: can't find referenced class org.tukaani.xz.SingleXZInputStream
Warning:org.apache.commons.compress.compressors.xz.XZCompressorInputStream: can't find referenced class org.tukaani.xz.XZ
Warning:org.apache.commons.compress.compressors.xz.XZCompressorOutputStream: can't find referenced class org.tukaani.xz.XZOutputStream
Warning:org.apache.commons.compress.compressors.xz.XZCompressorOutputStream: can't find referenced class org.tukaani.xz.LZMA2Options
Warning:org.apache.commons.compress.compressors.xz.XZCompressorOutputStream: can't find referenced class org.tukaani.xz.XZOutputStream
Warning:org.apache.commons.compress.compressors.xz.XZCompressorOutputStream: can't find referenced class org.tukaani.xz.LZMA2Options
Warning:org.apache.commons.compress.compressors.xz.XZCompressorOutputStream: can't find referenced class org.tukaani.xz.XZOutputStream
Warning:org.codehaus.jackson.map.ext.DOMSerializer: can't find referenced class org.w3c.dom.bootstrap.DOMImplementationRegistry
Warning:org.joda.time.DateMidnight: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.DateTime: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.DateTimeZone: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.DateTimeZone: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Days: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Days: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Duration: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Hours: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Hours: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Instant: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.LocalDate: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.LocalDate: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.LocalDateTime: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.LocalDateTime: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.LocalTime: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.LocalTime: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Minutes: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Minutes: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.MonthDay: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.MonthDay: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Months: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Months: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.MutableDateTime: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.MutableDateTime: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.MutablePeriod: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Period: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Seconds: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Seconds: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Weeks: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Weeks: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.YearMonth: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.YearMonth: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.Years: can't find referenced class org.joda.convert.FromString
Warning:org.joda.time.Years: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.base.AbstractDuration: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.base.AbstractInstant: can't find referenced class org.joda.convert.ToString
Warning:org.joda.time.base.AbstractPeriod: can't find referenced class org.joda.convert.ToString
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.HttpMethodBase
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.URI
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.URIException
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.HttpMethodBase
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.methods.EntityEnclosingMethod
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.methods.ByteArrayRequestEntity
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.methods.EntityEnclosingMethod
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.HttpClient
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.URIException
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.HttpMethodBase
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.URI
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.HttpClient
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.HttpMethodBase
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.HttpClient
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.HttpMethodBase
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.HttpClient
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.HttpMethodBase
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.URIException
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.methods.EntityEnclosingMethod
Warning:org.springframework.http.client.CommonsClientHttpRequest: can't find referenced class org.apache.commons.httpclient.methods.RequestEntity
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.HttpClient
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.MultiThreadedHttpConnectionManager
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.HttpClient
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.HttpConnectionManager
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.params.HttpConnectionManagerParams
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.methods.GetMethod
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.methods.DeleteMethod
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.methods.HeadMethod
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.methods.OptionsMethod
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.methods.PostMethod
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.methods.PutMethod
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.methods.TraceMethod
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.MultiThreadedHttpConnectionManager
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.HttpConnectionManager
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.params.HttpConnectionManagerParams
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.HttpClient
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.HttpMethodBase
Warning:org.springframework.http.client.CommonsClientHttpRequestFactory: can't find referenced class org.apache.commons.httpclient.HttpConnectionManager
Warning:org.springframework.http.client.CommonsClientHttpResponse: can't find referenced class org.apache.commons.httpclient.HttpMethod
Warning:org.springframework.http.client.CommonsClientHttpResponse: can't find referenced class org.apache.commons.httpclient.Header
Warning:org.springframework.http.client.CommonsClientHttpResponse: can't find referenced class org.apache.commons.httpclient.HttpMethod
Warning:org.springframework.http.client.CommonsClientHttpResponse: can't find referenced class org.apache.commons.httpclient.Header
Warning:org.springframework.http.client.CommonsClientHttpResponse: can't find referenced class org.apache.commons.httpclient.HttpMethod
Warning:org.springframework.http.client.CommonsClientHttpResponse: can't find referenced class org.apache.commons.httpclient.Header
Warning:org.springframework.http.client.CommonsClientHttpResponse: can't find referenced class org.apache.commons.httpclient.HttpMethod
Warning:org.springframework.http.client.CommonsClientHttpResponse: can't find referenced class org.apache.commons.httpclient.Header
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.WireFeedInput
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.FeedException
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.WireFeed
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.WireFeedOutput
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.WireFeed
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.WireFeedInput
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.FeedException
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.WireFeed
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.WireFeedOutput
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.WireFeed
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.FeedException
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.WireFeedInput
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.WireFeed
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.FeedException
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.WireFeed
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.WireFeedOutput
Warning:org.springframework.http.converter.feed.AbstractWireFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.WireFeed
Warning:org.springframework.http.converter.feed.AtomFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.atom.Feed
Warning:org.springframework.http.converter.feed.RssChannelHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.rss.Channel
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.synd.SyndFeed
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.SyndFeedInput
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.FeedException
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.synd.SyndFeed
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.SyndFeedOutput
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.SyndFeedInput
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.FeedException
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.synd.SyndFeed
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.SyndFeedOutput
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.synd.SyndFeed
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.FeedException
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.SyndFeedInput
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.synd.SyndFeed
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.FeedException
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.synd.SyndFeed
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.io.SyndFeedOutput
Warning:org.springframework.http.converter.feed.SyndFeedHttpMessageConverter: can't find referenced class com.google.code.rome.android.repackaged.com.sun.syndication.feed.synd.SyndFeed
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.databind.ObjectMapper
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.core.JsonFactory
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.core.JsonGenerator
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.databind.ObjectMapper
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.core.JsonEncoding
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.databind.JavaType
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.core.JsonEncoding
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.core.JsonGenerator
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.core.JsonEncoding
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.core.JsonFactory
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.core.JsonGenerator
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.core.JsonEncoding
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.databind.ObjectMapper
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.databind.JavaType
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.core.JsonEncoding
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.core.JsonGenerator
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.databind.JavaType
Warning:org.springframework.http.converter.json.MappingJackson2HttpMessageConverter: can't find referenced class com.fasterxml.jackson.core.JsonEncoding
Warning:org.springframework.http.converter.xml.SimpleXmlHttpMessageConverter: can't find referenced class org.simpleframework.xml.core.Persister
Warning:org.springframework.http.converter.xml.SimpleXmlHttpMessageConverter: can't find referenced class org.simpleframework.xml.Root
Warning:org.springframework.http.converter.xml.SimpleXmlHttpMessageConverter: can't find referenced class org.simpleframework.xml.Serializer
Warning:there were 276 unresolved references to classes or interfaces.
You may need to add missing library jars or update their versions.
If your code works fine without the missing classes, you can suppress
the warnings with '-dontwarn' options.
(http://proguard.sourceforge.net/manual/troubleshooting.html#unresolvedclass)

Experience here is coming from Eclipse and not Android Studio. I will typically have my proguard.cfg file in a location at the root level with the project. And the line inside my project.properties referencing the file would look something like this:
proguard.config=proguard.cfg
while you have this:
proguard.config=${sdk.dir}/tools/proguard/proguard-android.txt:proguard-project.txt
Do you also have a file names proguard-android.txt? I am unfamiliar with the style convention there in your command line. Perhaps it is a matter of not finding the right file?