RFR: 8299513: Clean up java.io [v9]

[Per Minborg]

> Code in java.io contains many legacy constructs and semantics not recommended including: 
> 
> * C-style array declaration 
> * Unnecessary visibility 
> * Redundant keywords in interfaces (e.g. public, static) 
> * Non-standard naming for constants 
> * Javadoc typos 
> * Missing final declaration 
> 
> These should be fixed as a sanity effort.

Per Minborg has updated the pull request incrementally with one additional commit since the last revision:

  Convert field to static and revert copyright year

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/11848/files
  - new: https://git.openjdk.org/jdk/pull/11848/files/5a4cb55e..b3d115ed

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11848&range=08
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11848&range=07-08

  Stats: 8 lines in 2 files changed: 2 ins; 3 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/11848.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11848/head:pull/11848

PR: https://git.openjdk.org/jdk/pull/11848