[jdk18u] RFR: 8278186: org.jcp.xml.dsig.internal.dom.Utils.parseIdFromSameDocumentURI throws StringIndexOutOfBoundsException when calling substring method

[Sean Coffey]

backport to jdk18u

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Commit messages:
 - Backport 1f1db838ab7d427170d59a8b55fdb45c4d80c359

Changes: https://git.openjdk.java.net/jdk18u/pull/34/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk18u&pr=34&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278186
  Stats: 75 lines in 4 files changed: 66 ins; 0 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk18u/pull/34.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18u pull/34/head:pull/34

PR: https://git.openjdk.java.net/jdk18u/pull/34