import com.atlassian.jira.ComponentManager
import com.atlassian.jira.issue.fields.CustomField
import com.atlassian.jira.issue.CustomFieldManager
import com.atlassian.jira.issue.label.LabelManager
 import org.springframework.util.StringUtils

labelManager = ComponentManager.getComponentInstanceOfType(LabelManager.class)
CustomFieldManager customFieldManager = ComponentManager.getInstance().getCustomFieldManager();


CustomField UseCustomer = customFieldManager.getCustomFieldObject(10600);
CustomField Customer = customFieldManager.getCustomFieldObject(10900);


//Remove all labels
labelManager.removeLabelsForCustomField(10900)
 
def componentManager = ComponentManager.getInstance()
def authContext = componentManager.getJiraAuthenticationContext()
def user = authContext.getUser()


//Set new label
labelManager.setLabels(currentUseruser, issue.id,issue.getCustomFieldValue(UseCustomer) as Set<set>, false,false)