Example migration of Android application from Java to Kotlin - DO NOT MERGE

[dbacinski]

Migration findings and solved issues:

• Java protected (package-private + inheritance) != Koltin protected (private + inheritance)
• there is no package-private scope to hide classes inside of package and expose just a public interface
• tests that verifies nulls are replaced with non-nullable Kotlin types
• nullable view has to be guarded with .?, because smart cast does't work for var-s
• builders can be replaced with constructor and named parameters
• Mockito is failing on final classes (Kotlin default), can be fixed by Mock Maker
• Mockito any() doesn't work for objects in Kotlin, alternative any() from mockito-kotlin can be used
• when is a keyword in Kotlin, use BDDMockito.given() instead
• Gradle annotationProcessor is replaced by kapt

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