If I create a shared JavaCompiler and shared JavaFileManager, then create different tasks using "-d" to specify different directories, only the first value is used. Subsequent ones appear to be ignored.

Workaround is to explicitly change location on filemanager, such as with StandardJavaFilemanager.setLocation.

Test case is upcoming new test
test/tools/javac/api/TestJavacTask_ParseEnterGen.java

Note use of setLocation instead of "-d" in options.