RFR: 8289384: Fix warnings: method does not override the inherited method since it is private to a different package

[Andy Goryachev]

The fix includes:
- renaming of offending methods to avoid confusion
- explicitly declaring the offending methods as private

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

Commit messages:
 - 8289384: fixed method does not override the inherited... warning

Changes: https://git.openjdk.org/jfx/pull/824/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=824&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289384
  Stats: 28 lines in 11 files changed: 1 ins; 0 del; 27 mod
  Patch: https://git.openjdk.org/jfx/pull/824.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/824/head:pull/824

PR: https://git.openjdk.org/jfx/pull/824