proguard.log

Note: there were 5 references to unknown classes.
      You should check your configuration for typos.
      (http://proguard.sourceforge.net/manual/troubleshooting.html#unknownclass)
Note: there were 3 classes trying to access enclosing classes using reflection.
      You should consider keeping the inner classes attributes
      (using '-keepattributes InnerClasses').
      (http://proguard.sourceforge.net/manual/troubleshooting.html#attributes)
Note: there were 208 unkept descriptor classes in kept class members.
      You should consider explicitly keeping the mentioned classes
      (using '-keep').
      (http://proguard.sourceforge.net/manual/troubleshooting.html#descriptorclass)
Note: there were 8 unresolved dynamic references to classes or interfaces.
      You should check if you need to specify additional program jars.
      (http://proguard.sourceforge.net/manual/troubleshooting.html#dynamicalclass)
Note: there were 4 accesses to class members by means of introspection.
      You should consider explicitly keeping the mentioned class members
      (using '-keep' or '-keepclassmembers').
      (http://proguard.sourceforge.net/manual/troubleshooting.html#dynamicalclassmember)
Warning:there were 5 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:Exception while processing task java.io.IOException: Please correct the above warnings first.
:app:transformClassesAndResourcesWithProguardForRelease FAILED
Error:Execution failed for task ':app:transformClassesAndResourcesWithProguardForRelease'.
> java.io.IOException: Please correct the above warnings first.
Information:BUILD FAILED
Information:Total time: 18.407 secs