RFR: 8280189: JFR: TestPrintXML should print mismatching XML

[Erik Gahlin]

Hi,

Could I have a review of this improvement to TestPrintXML?

Testing: jdk/jfr/tool/TestPrintXML.java

Thanks
Erik

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Commit messages:
 - Remove unused imports
 - More robust
 - Fixes
 - Formatting and copyright year
 - Initial

Changes: https://git.openjdk.java.net/jdk/pull/7140/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7140&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280189
  Stats: 23 lines in 1 file changed: 19 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7140.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7140/head:pull/7140

PR: https://git.openjdk.java.net/jdk/pull/7140