RFR: JDK-8281082: Improve javadoc references to JOSS

[Joe Darcy]

The references to JOSS, the Java Object Serialization Specification, are not done consistently in the API javadoc. This should be improved.

I'll update copyright years before pushing.

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Commit messages:
 - JDK-8281082: Improve javadoc references to JOSS

Changes: https://git.openjdk.java.net/jdk/pull/7315/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7315&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8281082
  Stats: 11 lines in 6 files changed: 3 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7315.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7315/head:pull/7315

PR: https://git.openjdk.java.net/jdk/pull/7315