for 5.0 each of the workflow api encodes vendor extensions in the documents that have useful information

x-pegasus:
createdBy: "vahi"
createdOn: "2020-07-10T23:05:15Z"
apiLang: "java"

also, we should pick apiLang from there and set it to the dax_api key reported in planner metrics . this is to make sure work done as part of PM-1299 is not broken in 5.0