code: public ConversationMessage sendConversationMessage(
              final String conversationId,
              final ConversationMessageRequest request
      ) throws UnauthorizedException, GeneralException {
          String url = String.format(
                  "%s%s/%s%s",
                  CONVERSATIONS_BASE_URL,
                  CONVERSATION_PATH,
                  conversationId,
                  CONVERSATION_MESSAGE_PATH
          );
          return messageBirdService.sendPayLoad(url, request, ConversationMessage.class);
      }
docs: Sends a message to an existing Conversation.
  
  @param conversationId Conversation to send message to.
  @param request        Message to send.
  @return The newly created message.