RFR: JDK-8297605 DelayQueue javadoc is confusing [v2]

[Viktor Klang]

> Clarifies the distinction between expiration of the head of DelayQueue and how it relates to `poll`, `take`, and `peek`. See discussion on https://bugs.openjdk.org/browse/JDK-8297605
> 
> @DougLea If possible, please weigh in on whether this is in line with your thoughts on the matter.

Viktor Klang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains one additional commit since the last revision:

  JDK-8297605 DelayQueue javadoc is confusing

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/12729/files
  - new: https://git.openjdk.org/jdk/pull/12729/files/6ef82915..df54e8a7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12729&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12729&range=00-01

  Stats: 519072 lines in 8393 files changed: 252325 ins; 163470 del; 103277 mod
  Patch: https://git.openjdk.org/jdk/pull/12729.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12729/head:pull/12729

PR: https://git.openjdk.org/jdk/pull/12729