Unable to call username in WORKERS API

Summary:

When using the WORKER API we are Unable to call for 'username' details.

Previously in the EMPLOYEE API we were able to call, see below.

Can someone please advise how to call this data in WORKERS (not a different api) 

Content (required):

Version (include the version you are using, if applicable):

11.13.18.02

Code Snippet (add any code snippets that support your topic, if applicable):

Below is the EMPLOYEE API

But WORKERS, Username is missing