java.lang.reflect.Modifier represents Java language modifiers. Since a previous iteration of JEP 401, the "identity" source modifier is removed, and only "value" source modifier exists. As a result, "identity" is no longer qualified to be present in `Modifier`. We should migrate all its uses to ClassFile.ACC_IDENTITY or AccessFlag.IDENTITY (which already correctly identifies itself not as a source modifier).

This also avoids the headache of Modifier.toString clashing over SYNCHRONIZED versus IDENTITY.