RFR: 8354724: Methods in java.io.Reader to read all characters and all lines [v21]

[Brian Burkhalter]

> Implement the requested methods and add a test thereof.

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

  8354724: Improve readAllAsString method of Reader returned by Reader.of

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/24728/files
  - new: https://git.openjdk.org/jdk/pull/24728/files/3cbaede9..04d89963

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24728&range=20
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24728&range=19-20

  Stats: 4 lines in 1 file changed: 3 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/24728.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24728/head:pull/24728

PR: https://git.openjdk.org/jdk/pull/24728