Unable to implement control on MoveIt: Parameter '~moveit_controller_manager' not specified

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I am struggling to implement a joint_trajectory_controller on Moveit.

I have: 1. Set up my controllers.yaml file

controller_list:
       - name: /nymble_arm_controller
         action_ns: joint_trajectory_action
         type: FollowJointTrajectory
         default: true
         joints:
             - base_swivel
             - arm_joint
             - elbow_joint  
             - wrist_pitch
             - wrist_yaw
             - wrist_roll

2.Implemented an action server node for joint_trajectory_action interface.

Action server I have implemented is from here

3.Created a moveit_planning_execution launch file as described here

This launch file contains the required controller_manager.launch file described here

4.Created a launch file to start action server and included above launch file.

I have gone through all the similar questions asked before but none has helped me.

Will be grateful for some help.