Generics warnings and problems

Reported by Russel on the list:

I have a method definition:

@Override public Object invokeMethod ( final Class sender , final Object receiver , final String methodName , final Object[] arguments, final boolean isCallToSuper, final boolean fromInsideClass ) {

in the definition of "class GantMetaClass extends DelegatingMetaClass".
I get a warning that Class should be parameterized – which is fine per
se, but . . . if I replace it with Class<?> I then get the error:

Multiple markers at this line

• Name clash: The method invokeMethod(Class<?>, Object, String, Object[], boolean, boolean) of type GantMetaClass has the same erasure as invokeMethod
  (Class, Object, String, Object[], boolean, boolean) of type DelegatingMetaClass but does not override it
• The method invokeMethod(Class<?>, Object, String, Object[], boolean, boolean) of type GantMetaClass must override a superclass method
• Class is a raw type. References to generic type Class<T> should be parameterized

The last line seems to be adding insult to injury! However, if I clean
the project and rebuild it goes away so that is at least truthful I
guess the error here is that the old error is being kept when it should
be removed. I have no idea if this is a GrEclipse or general JDT issue.
Removing the <?> causes similar behaviour, the red margin marker is
changed to yellow but the correct error message is added on top of the
existing one rather than replacing it, i.e. I get:

Multiple markers at this line

• Class is a raw type. References to generic type Class<T> should be parameterized
• overrides groovy.lang.DelegatingMetaClass.invokeMethod
• The method invokeMethod(Class<?>, Object, String, Object[], boolean, boolean) of type GantMetaClass must override a superclass method
• Name clash: The method invokeMethod(Class<?>, Object, String, Object[], boolean, boolean) of type GantMetaClass has the same erasure as invokeMethod
  (Class, Object, String, Object[], boolean, boolean) of type DelegatingMetaClass but does not override it