The annotations spec says:

When the compiler encounters an annotated package declaration, it must emit a synthetic interface named package-name.package-info with no superinterfaces or members (exculding those methods implicitly declared as per JLS 9.2). The synthetic interface has the default access level ("package-private"). The package-level annotations are stored in the RuntimeVisibleAnnotations and RuntimeInvisibleAnnotations attributes of the ClassFile structure.

This class file is not emitted.