RFR: 8322214: Return value of XMLInputFactory.getProperty() changed from boolean to String in JDK 22 early access builds

[Joe Wang]

Fix the get (return) operation by using the same method as that used for checking the values of the DTD features during the resolution process.

Note: this patch also addresses the issue reported in https://bugs.openjdk.org/browse/JDK-8322216

Test: new test added covers DTD properties for SAX/DOM/StAX.
         Existing tests passed.

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Commit messages:
 - 8322214: Return value of XMLInputFactory.getProperty() changed from boolean to String in JDK 22 early access builds

Changes: https://git.openjdk.org/jdk/pull/17252/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17252&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8322214
  Stats: 144 lines in 3 files changed: 140 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/17252.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17252/head:pull/17252

PR: https://git.openjdk.org/jdk/pull/17252