Error message on "Do so by passing the top qualifier from the given hierarchy." violation is not informative

If you create custom type hierarchy with subtyping checker, add polymorphic qualifier and pass to PolymorphicQualifier meta-annotation value() property class that is not top qualifier, you will get TypeSystemError that says something about bottom types, rather than that you have passed not the top qualifier. Debugging this can be quite tedious.

Example:

@DefaultQualifierInHierarchy
@SubtypeOf({})
@Target({ElementType.TYPE_USE, ElementType.TYPE_PARAMETER})
public @interface root { }

@SubtypeOf({
    foo.class, boo.class, goo.class
})
@Target({ElementType.TYPE_USE, ElementType.TYPE_PARAMETER})
public @interface bottom { }

@SubtypeOf(root.class)
@Target({ElementType.TYPE_USE, ElementType.TYPE_PARAMETER})
public @interface goo { }

@SubtypeOf(goo.class)
@Target({ElementType.TYPE_USE, ElementType.TYPE_PARAMETER})
public @interface foo { }

@SubtypeOf(goo.class)
@Target({ElementType.TYPE_USE, ElementType.TYPE_PARAMETER})
public @interface boo { }

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE_USE, ElementType.TYPE_PARAMETER})
@PolymorphicQualifier(goo.class)
public @interface polygoo { }

will get you this error.

Start by reproducing the Java custom type hierarchy and polymorphic qualifier example from the issue, then trace where the TypeSystemError for the invalid PolymorphicQualifier value is constructed. Done means the diagnostic explains that the supplied qualifier is not the top qualifier, rather than referring misleadingly to bottom types.