code: @Deprecated
      public <T extends Client<I, O>, R extends Client<I, O>, I extends Request, O extends Response>
      ClientDecorationBuilder add(Class<I> requestType, Class<O> responseType, Function<T, R> decorator) {
          return add0(requestType, responseType, decorator);
      }
docs: Adds a new decorator {@link Function}.
  
  @param requestType the type of the {@link Request} that the {@code decorator} is interested in
  @param responseType the type of the {@link Response} that the {@code decorator} is interested in
  @param decorator the {@link Function} that transforms a {@link Client} to another
  @param <T> the type of the {@link Client} being decorated
  @param <R> the type of the {@link Client} produced by the {@code decorator}
  @param <I> the {@link Request} type of the {@link Client} being decorated
  @param <O> the {@link Response} type of the {@link Client} being decorated
  
  @deprecated Use {@link #add(Function)} or {@link #addRpc(Function)}.