code: public ResolvableType getSuperType() {
  		Class<?> resolved = resolve();
  		if (resolved == null || resolved.getGenericSuperclass() == null) {
  			return NONE;
  		}
  		if (this.superType == null) {
  			this.superType = forType(SerializableTypeWrapper.forGenericSuperclass(resolved),
  					asVariableResolver());
  		}
  		return this.superType;
  	}
docs: Return a {@link ResolvableType} representing the direct supertype of this type.
  If no supertype is available this method returns {@link #NONE}.
  @see #getInterfaces()