Refactoring needed for JSONObject.populateMap()

[stleary]

See this recent SonarQube report:
https://sonarcloud.io/project/issues?issueStatuses=OPEN%2CCONFIRMED&pullRequest=983&id=stleary_JSON-java&open=AZb9I_F8fj3zpl20NBGj

Also, if the code review comments in #982 are not addressed before merge, include the recommended fixes here.

Note: Start work after #982 is merged

[stleary]

This issue is being fixed in #990

[stleary]

Closing due to issue fixed in #990