import com.atlassian.jira.component.ComponentAccessor
def fieldLayoutManager = ComponentAccessor.fieldLayoutManager
def projectManager = ComponentAccessor.projectManager
def projectId = projectManager.getProjectObjByName("Test Epic Link").id
def issueTypeId = ComponentAccessor.constantsManager.allIssueTypeObjects.find {
it.name == "Task"}.id
def fieldLayout = fieldLayoutManager.getFieldLayout(projectId, issueTypeId)
def editFieldLayout = fieldLayoutManager.getEditableFieldLayout(
fieldLayout.id)
def epicLinkField = ComponentAccessor.customFieldManager.customFieldObjects.find {
it.name == "Epic Link" }
def fieldLayoutItem = editFieldLayout.getFieldLayoutItem(epicLinkField)
editFieldLayout.makeRequired(fieldLayoutItem)
fieldLayoutManager.storeEditableFieldLayout(editFieldLayout)