Limit a Behaviour to a Specific Workflow Action

import groovy.transform.BaseScript
import com.onresolve.jira.groovy.user.FieldBehaviours

@BaseScript FieldBehaviours fieldBehaviours

final expectedActionName = 'Start Progress'
final expectedDestinationName = 'Done'
final fieldName = 'Some Field'

def field = getFieldByName(fieldName)

actionName == expectedActionName || destinationStepName == expectedDestinationName ?
    field.setRequired(true) :
    field.setRequired(false)