RFR: 8312475: org.jline.util.PumpReader signed byte problem

[Michal Sobierski]

Added casting to `& 0xFF` to the InputStream read method return value.

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Commit messages:
 - 8312475: org.jline.util.PumpReader signed byte problem

Changes: https://git.openjdk.org/jdk/pull/16053/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16053&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8312475
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/16053.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16053/head:pull/16053

PR: https://git.openjdk.org/jdk/pull/16053