Fix to support incremental builds

[DJViking]

The compileJava is always not up-to-date because of the moduleplugin

Task ':compileJava' is not up-to-date because:
  Task ':compileJava' has an additional action that was implemented by the Java lambda 
 'org.javamodularity.moduleplugin.tasks.CompileTask$$Lambda$2
15/0x00000001005d0040'. Using Java lambdas is not supported, use an (anonymous) inner class instead.
All input files are considered out-of-date for incremental task ':compileJava'.

Does not matter if there is no changes in the java source, it will always run compileJava.

[DJViking]

I have made these changes and will submit a merge request.

[paulbakker]

merged

[tlinkowski]

For documentation purposes

Java lambdas cannot be used in the plugin only as task inputs (e.g. Task.doFirst, Task.doLast).

Whenever a receiver is not a task input (e.g. Project.afterEvaluate, Distribution.contents), it's fine to use Java lambdas.

More info: gradle/gradle#5510 (comment)