Although "java.base" is mandated to be included, it is also inserted automatically by the compiler. Isn't anything automatically inserted by the compiler considered synthetic? When I examine the class file, I get ACC_MANDATED but not ACC_SYNTHETIC for this export. I believe both should be there.
Furthermore, the user is allowed to explicitly ask for "java.base" to be a requirement. When this happens, I think ACC_SYNTHETIC should not be included. Cheers, Paul