<AWT Dev> RFR: 8252195: AWT Accessibility API nested classes rely on default constructors

[Phil Race]

https://bugs.openjdk.java.net/browse/JDK-8252195
is another one of the issues adding missing explicit no-args constructors in the desktop module.

As well as being nested, these are all concrete, but protected, classes and so the constructors
are protected.

CSR here https://bugs.openjdk.java.net/browse/JDK-8253450 needs a reviewer too.

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Commit messages:
 - 8252195: AWT Accessibility API nested classes rely on default constructors
 - 8252195: AWT Accessibility API nested classes rely on default constructors

Changes: https://git.openjdk.java.net/jdk/pull/288/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=288&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8252195
  Stats: 117 lines in 19 files changed: 117 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/288.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/288/head:pull/288

PR: https://git.openjdk.java.net/jdk/pull/288