Plugin doesnt work with gradle > 4.8 (using packages with java-source throws ClassNotFoundException's)

[jneira]

It seems to throw ClassNotFoundExceptions for used packages with classes included in the java-source stanza.
Reported by @politrons in typelead/eta#904

[jneira]

The workaround is to use gradle 4.7 or 4.8, locally installed or using the gradle wrapper used in examples