proguard problems in android studio
<p>I've develop an app in android studio. It works fine in debug version but when I try to create a release version with proguard, hundreds of warnings appear and I'm not able to get rid of them using -keep option. </p>

<p>My build.gradle is</p>

<pre><code>apply plugin: 'com.android.application'
apply plugin: 'maven'
apply plugin: 'com.google.gms.google-services'


android {
    compileSdkVersion 23
    buildToolsVersion "23.0.2"

    defaultConfig {
        applicationId "com.ruben.xradar"
        minSdkVersion 19
        targetSdkVersion 23
        versionCode 22
        versionName "0.22"
        multiDexEnabled true
    }

    dexOptions {
        javaMaxHeapSize "4g"
    }
    packagingOptions {
        exclude 'META-INF/NOTICE.txt'
        exclude 'META-INF/LICENSE.txt'
    }

    buildTypes {
        release {
            //Esto es para oscurecer y minificar el código
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
        debug {
            debuggable false
        }
    }
}

dependencies {
    compile(project(path: ':backend', configuration: 'android-endpoints')) {
        exclude group: 'com.google.guava'
    }
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile('joda-time:joda-time:2.8.2') {}

    //para el doble slider
    compile 'com.appyvet:materialrangebar:1.3'
    //para logearse usando la cuenta de redes sociales
    compile files('src/libs/socialauth-4.12.jar')
    compile 'commons-io:commons-io:2.4'
    //google cloud messaging
    compile 'com.google.android.gms:play-services:8.3.0'
    compile 'com.google.android.gms:play-services-ads:8.3.0'
    compile 'com.google.android.gms:play-services-analytics:8.3.0'
    compile 'com.google.android.gms:play-services-identity:8.3.0'
    compile 'com.google.android.gms:play-services-gcm:8.3.0'
    compile 'com.google.android.gms:play-services-auth:8.3.0'
    //para hacer el stepper del registro
    compile 'ivb.com.materialstepper:material-stepper:0.0.2'
    //para poder usar material design en versiones pre-lollipop
    compile 'com.android.support:appcompat-v7:23.2.0'
    compile 'com.android.support:cardview-v7:23.2.0'
    compile 'com.android.support:recyclerview-v7:23.2.0'
    compile 'com.android.support:palette-v7:23.2.0'
    compile 'com.android.support:support-v4:23.2.0'
    compile 'com.android.support:design:23.2.0'
    compile 'com.android.support:multidex:1.0.1'

    //esto es para los díalogos de cambiar las fotos
    compile 'com.kingfisherphuoc:quick-action-dialog-fragment:1.1'
    //para animar el recyclerview
    compile 'jp.wasabeef:recyclerview-animators:1.3.0'
    //para usar iconos de fuentes, svg's como iconos y así no tener que            crear carpetas hdpi,mdpi,xhdpi, etc
    compile 'com.mikepenz:iconics-core:2.5.8@aar'
    compile 'com.mikepenz:google-material-typeface:2.2.0.1.original@aar'

    //para hacer imageviews redondos
    compile 'de.hdodenhof:circleimageview:2.0.0'
}
</code></pre>

<p>and finally the proguard wargings messages are:</p>

<pre><code>Warning:com.google.api.client.googleapis.testing.TestUtils: can't find referenced class com.google.common.base.Splitter
Warning:com.google.api.client.googleapis.testing.TestUtils: can't find referenced class com.google.common.collect.Lists
Warning:com.google.api.client.googleapis.testing.TestUtils: can't find referenced class com.google.common.base.Splitter
Warning:com.google.api.client.googleapis.testing.TestUtils: can't find referenced class com.google.common.collect.Lists
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator: can't find referenced method 'void dispatchMoveFinished(android.support.v7.widget.RecyclerView$ViewHolder)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator: can't find referenced method 'void dispatchChangeFinished(android.support.v7.widget.RecyclerView$ViewHolder,boolean)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator: can't find referenced method 'void dispatchRemoveFinished(android.support.v7.widget.RecyclerView$ViewHolder)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator: can't find referenced method 'void dispatchAddFinished(android.support.v7.widget.RecyclerView$ViewHolder)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator$4: can't find referenced method 'void dispatchMoveStarting(android.support.v7.widget.RecyclerView$ViewHolder)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator$4: can't find referenced method 'void dispatchMoveFinished(android.support.v7.widget.RecyclerView$ViewHolder)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator$5: can't find referenced method 'void dispatchChangeStarting(android.support.v7.widget.RecyclerView$ViewHolder,boolean)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator$5: can't find referenced method 'void dispatchChangeFinished(android.support.v7.widget.RecyclerView$ViewHolder,boolean)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator$6: can't find referenced method 'void dispatchChangeStarting(android.support.v7.widget.RecyclerView$ViewHolder,boolean)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator$6: can't find referenced method 'void dispatchChangeFinished(android.support.v7.widget.RecyclerView$ViewHolder,boolean)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator$DefaultAddVpaListener: can't find referenced method 'void dispatchAddStarting(android.support.v7.widget.RecyclerView$ViewHolder)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator$DefaultAddVpaListener: can't find referenced method 'void dispatchAddFinished(android.support.v7.widget.RecyclerView$ViewHolder)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator$DefaultRemoveVpaListener: can't find referenced method 'void dispatchRemoveStarting(android.support.v7.widget.RecyclerView$ViewHolder)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:jp.wasabeef.recyclerview.animators.BaseItemAnimator$DefaultRemoveVpaListener: can't find referenced method 'void dispatchRemoveFinished(android.support.v7.widget.RecyclerView$ViewHolder)' in program class jp.wasabeef.recyclerview.animators.BaseItemAnimator
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.consumer.ConsumerManager
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.ax.FetchRequest
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.AuthRequest
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.OpenIDException
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.ParameterList
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.consumer.ConsumerManager
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.consumer.VerificationResult
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.discovery.Identifier
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.consumer.VerificationResult
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.AuthSuccess
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.ax.FetchResponse
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.consumer.ConsumerException
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.OpenIDException
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.ParameterList
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.consumer.VerificationResult
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.discovery.Identifier
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.AuthSuccess
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.ax.FetchResponse
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.ax.FetchRequest
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.AuthRequest
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.consumer.VerificationResult
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.discovery.Identifier
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.consumer.ConsumerManager
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.discovery.DiscoveryInformation
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.AuthRequest
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.ax.FetchRequest
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.OpenIDException
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.ax.FetchResponse
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.AuthSuccess
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.message.ParameterList
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.consumer.VerificationResult
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.discovery.Identifier
Warning:org.brickred.socialauth.provider.OpenIdImpl: can't find referenced class org.openid4java.OpenIDException
Warning:org.brickred.socialauth.util.SocialAuthUtil: can't find referenced class javax.servlet.http.HttpServletRequest
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
Note: android.support.v4.media.IMediaBrowserServiceCallbacksAdapterApi21: can't find dynamically referenced class android.service.media.IMediaBrowserServiceCallbacks
Note: android.support.v4.media.IMediaBrowserServiceCallbacksAdapterApi21: can't find dynamically referenced class android.content.pm.ParceledListSlice
Note: android.support.v4.media.IMediaBrowserServiceCallbacksAdapterApi21$Stub: can't find dynamically referenced class android.service.media.IMediaBrowserServiceCallbacks$Stub
Note: android.support.v4.media.ParceledListSliceAdapterApi21: can't find dynamically referenced class android.content.pm.ParceledListSlice
Note: android.support.v4.text.ICUCompatApi23: can't find dynamically referenced class libcore.icu.ICU
Note: android.support.v4.text.ICUCompatIcs: can't find dynamically referenced class libcore.icu.ICU
Note: android.support.v7.widget.DrawableUtils: can't find dynamically referenced class android.graphics.Insets
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.Session
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.FacebookSdk
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.Session
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.CallbackManager$Factory
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.login.LoginManager
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.CallbackManager
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.FacebookCallback
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.FacebookSdk
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.login.LoginManager
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.Session
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.login.LoginManager
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.Session$OpenRequest
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.Session
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.Session$StatusCallback
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.FacebookCallback
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.Session
Note: com.google.android.gms.internal.zzlf: can't find dynamically referenced class com.facebook.Session$StatusCallback
Note: com.google.android.gms.internal.zzlf$1: can't find dynamically referenced class com.facebook.login.LoginResult
Note: com.google.android.gms.internal.zzlf$1: can't find dynamically referenced class com.facebook.FacebookException
Note: com.google.android.gms.internal.zzlf$1: can't find dynamically referenced class com.facebook.AccessToken
Note: com.google.android.gms.internal.zzlf$2: can't find dynamically referenced class com.facebook.SessionState
Note: com.google.android.gms.maps.internal.zzy: can't find dynamically referenced class com.google.android.gms.maps.internal.CreatorImpl
Note: com.google.api.client.util.IOUtils: can't find dynamically referenced class java.nio.file.Files
Note: com.google.api.client.util.IOUtils: can't find dynamically referenced class java.nio.file.Path
Note: com.mikepenz.iconics.Iconics calls '(com.mikepenz.iconics.typeface.ITypeface)Class.forName(variable).newInstance()'
Note: org.joda.time.DateTimeZone calls '(org.joda.time.tz.Provider)Class.forName(variable).newInstance()'
Note: org.joda.time.DateTimeZone calls '(org.joda.time.tz.NameProvider)Class.forName(variable).newInstance()'
Note: android.support.v4.app.NotificationCompatJellybean accesses a declared field 'icon' dynamically
      Maybe this is program field 'android.support.design.R$attr { int icon; }'
      Maybe this is program field 'android.support.design.R$id { int icon; }'
      Maybe this is program field 'android.support.v4.app.NotificationCompat$Action { int icon; }'
      Maybe this is program field 'android.support.v7.appcompat.R$attr { int icon; }'
      Maybe this is program field 'android.support.v7.appcompat.R$id { int icon; }'
      Maybe this is program field 'android.support.v7.mediarouter.R$attr { int icon; }'
      Maybe this is program field 'android.support.v7.mediarouter.R$id { int icon; }'
      Maybe this is program field 'com.kingfisherphuoc.quickactiondialog.R$attr { int icon; }'
      Maybe this is program field 'com.kingfisherphuoc.quickactiondialog.R$id { int icon; }'
      Maybe this is program field 'com.mikepenz.google_material_typeface_library.R$attr { int icon; }'
      Maybe this is program field 'com.mikepenz.google_material_typeface_library.R$id { int icon; }'
      Maybe this is program field 'com.mikepenz.iconics.core.R$attr { int icon; }'
      Maybe this is program field 'com.mikepenz.iconics.core.R$id { int icon; }'
      Maybe this is program field 'com.mikepenz.iconics.utils.StyleContainer { java.lang.String icon; }'
      Maybe this is program field 'com.ruben.xradar.R$attr { int icon; }'
      Maybe this is program field 'com.ruben.xradar.R$id { int icon; }'
      Maybe this is program field 'ivb.com.materialstepper.R$attr { int icon; }'
      Maybe this is program field 'ivb.com.materialstepper.R$id { int icon; }'
      Maybe this is program field 'jp.wasabeef.recyclerview.R$attr { int icon; }'
      Maybe this is program field 'jp.wasabeef.recyclerview.R$id { int icon; }'
      Maybe this is program field 'org.brickred.socialauth.android.SocialAuthDialog { android.graphics.drawable.Drawable icon; }'
      Maybe this is library field 'android.R$attr { int icon; }'
      Maybe this is library field 'android.R$id { int icon; }'
      Maybe this is library field 'android.app.LauncherActivity$ListItem { android.graphics.drawable.Drawable icon; }'
      Maybe this is library field 'android.app.Notification { int icon; }'
      Maybe this is library field 'android.app.Notification$Action { int icon; }'
      Maybe this is library field 'android.appwidget.AppWidgetProviderInfo { int icon; }'
      Maybe this is library field 'android.content.pm.PackageItemInfo { int icon; }'
      Maybe this is library field 'android.content.pm.ResolveInfo { int icon; }'
      Maybe this is library field 'android.inputmethodservice.Keyboard$Key { android.graphics.drawable.Drawable icon; }'
      Maybe this is library field 'android.speech.tts.TextToSpeech$EngineInfo { int icon; }'
Note: android.support.v4.app.NotificationCompatJellybean accesses a declared field 'title' dynamically
      Maybe this is program field 'android.support.design.R$attr { int title; }'
      Maybe this is program field 'android.support.design.R$id { int title; }'
      Maybe this is program field 'android.support.v4.app.NotificationCompat$Action { java.lang.CharSequence title; }'
      Maybe this is program field 'android.support.v7.appcompat.R$attr { int title; }'
      Maybe this is program field 'android.support.v7.appcompat.R$id { int title; }'
      Maybe this is program field 'android.support.v7.mediarouter.R$attr { int title; }'
      Maybe this is program field 'android.support.v7.mediarouter.R$id { int title; }'
      Maybe this is program field 'com.google.android.gms.games.internal.player.PlayerColumnNames { java.lang.String title; }'
      Maybe this is program field 'com.google.android.gms.vision.barcode.Barcode$ContactInfo { java.lang.String title; }'
      Maybe this is program field 'com.google.android.gms.vision.barcode.Barcode$UrlBookmark { java.lang.String title; }'
      Maybe this is program field 'com.google.api.client.util.PemReader$Section { java.lang.String title; }'
      Maybe this is program field 'com.kingfisherphuoc.quickactiondialog.R$attr { int title; }'
      Maybe this is program field 'com.kingfisherphuoc.quickactiondialog.R$id { int title; }'
      Maybe this is program field 'com.mikepenz.google_material_typeface_library.R$attr { int title; }'
      Maybe this is program field 'com.mikepenz.google_material_typeface_library.R$id { int title; }'
      Maybe this is program field 'com.mikepenz.iconics.core.R$attr { int title; }'
      Maybe this is program field 'com.mikepenz.iconics.core.R$id { int title; }'
      Maybe this is program field 'com.ruben.xradar.R$attr { int title; }'
      Maybe this is program field 'com.ruben.xradar.R$id { int title; }'
      Maybe this is program field 'ivb.com.materialstepper.R$attr { int title; }'
      Maybe this is program field 'ivb.com.materialstepper.R$id { int title; }'
      Maybe this is program field 'jp.wasabeef.recyclerview.R$attr { int title; }'
      Maybe this is program field 'jp.wasabeef.recyclerview.R$id { int title; }'
      Maybe this is program field 'org.brickred.socialauth.Photo { java.lang.String title; }'
      Maybe this is program field 'org.brickred.socialauth.Position { java.lang.String title; }'
      Maybe this is library field 'android.R$attr { int title; }'
      Maybe this is library field 'android.R$id { int title; }'
      Maybe this is library field 'android.app.Notification$Action { java.lang.CharSequence title; }'
      Maybe this is library field 'android.preference.PreferenceActivity$Header { java.lang.CharSequence title; }'
Note: android.support.v4.app.NotificationCompatJellybean accesses a declared field 'actionIntent' dynamically
      Maybe this is program field 'android.support.v4.app.NotificationCompat$Action { android.app.PendingIntent actionIntent; }'
      Maybe this is library field 'android.app.Notification$Action { android.app.PendingIntent actionIntent; }'
Note: com.google.api.client.googleapis.auth.oauth2.DefaultCredentialProvider accesses a field 'environment' dynamically

etc, etc...
</code></pre>

<p>I don't know why, for example, adding -keep class jp.wasabeef.** {*;} do not dissapear warnings concerning to jp.wasabeef.</p>

<p>Can anyone help me?</p>