IssueTracker

@Mario Did you get a chance to try the build with -Pandroid.useDexArchive=false flag?

I'm the college of @Mario and I make it work without issues and without using  -Pandroid.useDexArchive=false by using alpha6 and removing retrolambda

Sorry my comment from Apr 21, 2017 12:41PM was wrong.
With -Pandroid.useDexArchive=false it looks like this

:app:transformClassesWithDesugarForNonpayItalyCompatDebugAndroidTest
:app:transformClassesWithPreDexForNonpayItalyCompatDebugAndroidTest
Dex: warning: Ignoring InnerClasses attribute for an anonymous inner class
(org.ccil.cowan.tagsoup.Parser$1) that doesn't come with an
associated EnclosingMethod attribute. This class was probably produced by a
compiler that did not target the modern .class file format. The recommended
solution is to recompile the class from source, using an up-to-date compiler
and without specifying any "-target" type options. The consequence of ignoring
this warning is that reflective operations on this class will incorrectly
indicate that it is *not* an inner class.

:app:transformDexWithDexForNonpayItalyCompatDebugAndroidTest FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:transformDexWithDexForNonpayItalyCompatDebugAndroidTest'.
> com.android.build.api.transform.TransformException: com.android.ide.common.process.ProcessException: java.util.concurrent.ExecutionException: com.android.dex.DexIndexOverflowException: method ID not in [0, 0xffff]: 65536

We updated our example repo https://github.com/originx/Gradle_troubles_android_enteprise where you can see the issue.
Just run

./gradlew spoonGermanyDebugAndroidTest
or
./gradlew spoonGermanyDebugAndroidTest -Pandroid.useDexArchive=false

and you will see the issue

Your tests do not fit into a single dex file. I've tried plugin 2.3.0 (I've also had to enable retrolambda for app, core, and pay modules), and the number of references that are generated is higher than 64k.
Please note that if you are using plugin's internal or Retrolamba support for Java 8 language features, for each lambda expression you will generate 3 additional references, so it might affect your reference count quite significantly.