Ok, well, start at https://developer.atlassian.com/display/JIRADEV/JIRA+REST+APIs - there's a good introduction to using the Jira REST API, and examples, inlcuding stuff about fetching custom field data.
I'm sorry, but now you're just randomly quoting bits of the system without any explanation of whatever you are thinking.
Please, look at the previous answers, work through what they say, and then post relevant questions, or you simply won't get any help.
What you've just done here is a bit like:
... can you see why we're confused?
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