RFR: 7569: Improve the implementation of Twitter plugin

[Suchita Chaturvedi]

Modified the Twitter plugin implementation a bit for a better approach.

-------------

Commit messages:
 - 7569: Improve the implementation of Twitter plugin

Changes: https://git.openjdk.java.net/jmc/pull/384/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=384&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-7569
  Stats: 26 lines in 2 files changed: 7 ins; 9 del; 10 mod
  Patch: https://git.openjdk.java.net/jmc/pull/384.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/384/head:pull/384

PR: https://git.openjdk.java.net/jmc/pull/384