RFR: 8314662: jshell shows duplicated signatures of javap

Wed Aug 30 11:00:38 UTC 2023

The Scope may contain duplicated entries (e.g. for duplicated static imports, as in this case), which may then show as duplicate signatures in JShell.

The proposal here is to avoid using the duplicates, by using `LinkedHashSet`.

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Commit messages:
 - 8314662: jshell shows duplicated signatures of javap

Changes: https://git.openjdk.org/jdk/pull/15489/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15489&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314662
  Stats: 16 lines in 2 files changed: 13 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/15489.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15489/head:pull/15489

PR: https://git.openjdk.org/jdk/pull/15489