RFR: 5041655: (ch) FileLock: negative param and overflow issues [v4]

[Brian Burkhalter]

> Add an implementation note to `java.nio.channels.FileLock.overlaps(long,long)` indicating that the method does not check its parameters. Adding such checks would be an incompatible change.

Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:

  5041655: Move size zero handling to file channel impl classes

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7254/files
  - new: https://git.openjdk.java.net/jdk/pull/7254/files/30ce90ce..e5d88e23

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7254&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7254&range=02-03

  Stats: 42 lines in 6 files changed: 17 ins; 7 del; 18 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7254.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7254/head:pull/7254

PR: https://git.openjdk.java.net/jdk/pull/7254