RFR: 8313961: Enhance identification of special serialization methods

[Raffaello Giulietti]

This improves the identification of the serialization magic fields and methods.

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Commit messages:
 - 8313961: Enhance identification of special serialization methods
 - 8313961: Enhance identification of special serialization methods
 - Merge branch 'master' into 8313961
 - 8313961: Enhance identification of special serialization methods
 - Merge branch 'master' into 8313961
 - Using getDeclaredMethod() in getInheritableMethod().
 - Using getDeclaredMethod() in getPrivateMethod().

Changes: https://git.openjdk.org/jdk/pull/15364/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15364&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8313961
  Stats: 349 lines in 4 files changed: 322 ins; 13 del; 14 mod
  Patch: https://git.openjdk.org/jdk/pull/15364.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15364/head:pull/15364

PR: https://git.openjdk.org/jdk/pull/15364