RFR: 8264859: Implement Context-Specific Deserialization Filters [v6]

[Roger Riggs]

> JEP 415: Context-specific Deserialization Filters extends the deserialization filtering mechanisms with more flexible and customizable protections against malicious deserialization.  See JEP 415: https://openjdk.java.net/jeps/415.
> The `java.io.ObjectInputFilter` and `java.io.ObjectInputStream` classes are extended with additional
> configuration mechanisms and filter utilities.
> 
> javadoc for `ObjectInputFilter`, `ObjectInputFilter.Config`, and `ObjectInputStream`:
>     http://cr.openjdk.java.net/~rriggs/filter-factory/java.base/java/io/ObjectInputFilter.html

Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:

  Review suggestions included;
  Added @implSpec for default methods in OIF;
  Added restriction that the filter factory cannot be set after an ObjectInputStream has been created and applied the current filter factory

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3996/files
  - new: https://git.openjdk.java.net/jdk/pull/3996/files/0274fb4f..f1a797a5

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3996&range=05
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3996&range=04-05

  Stats: 189 lines in 2 files changed: 95 ins; 27 del; 67 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3996.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3996/head:pull/3996

PR: https://git.openjdk.java.net/jdk/pull/3996