AdlVoid.java not included in generated runtime if Void not the source adl

[gmhta]

adlc version 1.1.4

For the following adl

module hw {
struct HW {};
};

adlc java -O out --generate-transitive --include-rt hw.adl

AdlVoid.java is not written to out/org/adl/runtime/. This break javac as Factories.java, JsonBindings & MaybeHelpers.java depend on it.