code: public void updateTaskDef(TaskDef taskDef) {
          Preconditions.checkNotNull(taskDef, "Task definition cannot be null");
          stub.updateTask(
                  MetadataServicePb.UpdateTaskRequest.newBuilder()
                          .setTask(protoMapper.toProto(taskDef))
                          .build()
          );
      }
docs: Updates an existing task definition
  
  @param taskDef the task definition to be updated