I faced this error during generating apk using idea13
ProGuard: Warning: butterknife.internal.InjectViewProcessor: can\'t find superclass or interface javax.ann
If anyone does face an issue with Proguard and Butterknife, use the following given at http://jakewharton.github.io/butterknife/index.html#proguard
-keep class butterknife.** { *; }
-dontwarn butterknife.internal.**
-keep class **$$ViewBinder { *; }
-keepclasseswithmembernames class * {
@butterknife.* ;
}
-keepclasseswithmembernames class * {
@butterknife.* ;
}