code: @SuppressWarnings("unchecked")
      public <E extends Throwable> ExceptionHandler<? super E>
      removeExceptionHandler(Class<E> type) {
          exceptionHandlerCache.clear();
          return (ExceptionHandler<? super E>) exceptionHandlers.remove(type);
      }
docs: Deregisters a {@link MessageHandler} that receives the messages of
  the specified <code>type</code>.
  
  @return the removed handler if successfully removed.  <tt>null</tt> otherwise.