code: private <T extends CommandType> T getCommand() {
          if (command == null) {
              if (getPayload() instanceof String) {
                  this.command = (T) marshaller.unmarshal(new StringSource(getPayload(String.class)));
              }
          }
  
          return (T) command;
      }
docs: Gets the command if any or tries to unmarshal String payload representation to an command model.
  @return