This is how to create and configure an SLA custom field :
we will find the calendar that we create in the first step ( I. Create a working calendar)
For the green level, we will add a notification action
For the orange level, we will add a custom action following the steps::
1.create the groovy file in the following path: Atlassian/Jira/KeplerTechnologies/custom-actions, The groovy filename is: ActionToDo
2. Come back to the configuration, and add the groovy filename in the new action
For the Red level, we will add both actions (notification and custom action),
By clicking on the button 'Done', the configuration of the SLA will be saved.