code: public final SgClass create(final String implPackageName, final String implClassName,
              final ImplementationFactoryListener listener, final Class<?>... intf) {
          return create(implPackageName, implClassName, null, null, listener, intf);
      }
docs: Creates an implementation of the interface.
  
  @param implPackageName
  Name of the implementation package - Cannot be null.
  @param implClassName
  Name of the implementation class - Cannot be null.
  @param listener
  Creates the bodies for all methods - Cannot be null.
  @param intf
  One or more interfaces.
  
  @return New object implementing the interface.