code: public String send(String payload) throws CommandExecutionException {
          if (payload == null) throw new CommandExecutionException(CommandExecutionException.Error.INVALID_PARAMETERS);
          if (deviceID == -1 || timeStamp == -1 || token == null || ip == null) {
              if (!discover()) throw new CommandExecutionException(CommandExecutionException.Error.DEVICE_NOT_FOUND);
          }
          if (methodID >= 10000) methodID = 1;
          if (ip == null || token == null) throw new CommandExecutionException(CommandExecutionException.Error.IP_OR_TOKEN_UNKNOWN);
          if (socket == null) return null;
          timeStamp++;
          Command msg = new Command(this.token,this.deviceID,timeStamp,this.methodID,"", null);
          methodID++;
          int retriesLeft = this.retries;
          while (true) {
              try {
                  byte[] resp = send(msg.create(payload));
                  if (!Response.testMessage(resp, this.token)) throw new CommandExecutionException(CommandExecutionException.Error.INVALID_RESPONSE);
                  if (resp.length > 0x20) {
                      byte[] pl = new byte[resp.length - 0x20];
                      System.arraycopy(resp, 0x20, pl, 0, pl.length);
                      String payloadString = Response.decryptPayload(pl, this.token);
                      if (payloadString == null) throw new CommandExecutionException(CommandExecutionException.Error.INVALID_RESPONSE);
                      return payloadString;
                  }
              } catch (CommandExecutionException e) {
                  if (retriesLeft > 0){
                      retriesLeft--;
                      continue;
                  }
                  throw e;
              }
          }
      }
docs: Send an arbitrary string as payload to the device.
  @param payload The string to send.
  @return The response of the device as an unparsed string.
  @throws CommandExecutionException When there has been a error during the communication or the response was invalid.