Script Runner Call REST / Issue as a JSON

Hello, I would Like to ask, if I need to convert IssueObject to JSON in scriptConsole, (Issue as a object is not serialized, but there is option in IssueBean object, unfortunetely I can not call IssueBeanBuilder2 because of unavailable of some Manager in script.)

So I decided call JIRA Rest:

Problem is I can not call this REST in groovy script as authentificated JIRA logged in user, because ScriptRunner do not use my active credentials.

Question is: Is there any way how to call JIRA Rest from groovy script as actual logged in user?
Or some other way how to convert JIRA Issue object to JSON?

Possible ways: