[Java] Update gradle build script so IDEA recognises generated code.
[Java] Update gradle build script so IDEA recognises generated code.

PKRoma/simple-binary-encoding,PKRoma/simple-binary-encoding,PKRoma/simple-binary-encoding,PKRoma/simple-binary-encoding,PKRoma/simple-binary-encoding,real-logic/simple-binary-encoding,real-logic/simple-binary-encoding,real-logic/simple-binary-encoding,PKRoma/simple-binary-encoding,real-logic/simple-binary-encoding,real-logic/simple-binary-encoding,PKRoma/simple-binary-encoding,real-logic/simple-binary-encoding,real-logic/simple-binary-encoding