code: public <T> T callFunction(
        final String name,
        final List<?> args,
        final @Nullable Long requestTimeout,
        final Class<T> resultClass,
        final CodecRegistry codecRegistry
    ) {
      return this.functionService
          .withCodecRegistry(codecRegistry)
          .callFunction(name, args, requestTimeout, resultClass);
    }
docs: Calls the specified Stitch function, and decodes the response into an instance of the specified
  type. The response will be decoded using the codec registry given.
  
  @param name the name of the Stitch function to call.
  @param args the arguments to pass to the Stitch function.
  @param requestTimeout the number of milliseconds the client should wait for a response from the
  server before failing with an error.
  @param resultClass the class that the Stitch response should be decoded as.
  @param <T> the type into which the Stitch response will be decoded.
  @param codecRegistry the codec registry that will be used to encode/decode the function call.
  @return the decoded value.