Good one. I can think of a possible usage of the seconde message:

var incidentGR = new GlideRecord('incident');
incidentGR.addEncodedQuery('state=1^caller_id=77ad8176731313005754660c4cf6a7de'); //David Miller

var updateData = {"caller_id": "6816f79cc0a8016401c5a33be04be441"}; //Martin Ivanov

new GlideRecordUtil().mergeToGR(updateData , incidentGR);

incidentGR.updateMultiple();