code: public static GUID getIID( Class<?> _interface ) {
          IID iid = _interface.getAnnotation(IID.class);
          if(iid==null)
              throw new IllegalArgumentException(_interface.getName()+" doesn't have @IID annotation");
          return new GUID(iid.value());
      }
docs: Gets the interface GUID associated with the given interface.
  
  <p>
  This method retrieves the associated {@link IID} annotation from the
  interface and return it.
  
  @param _interface reference to an object that has the {@link IID} annotation.
  @return always return no-null valid {@link GUID} object.
  @throws IllegalArgumentException if the interface doesn't have any {@link IID} annotation.