RFR: 8347427: JTabbedPane/8134116/Bug8134116.java has no license header

[Alexey Ivanov]

The file `test/jdk/javax/swing/JTabbedPane/8134116/Bug8134116.java` has no license header.

I added the GPL header and organised imports.

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Commit messages:
 - 8347427: JTabbedPane/8134116/Bug8134116.java has no license header

Changes: https://git.openjdk.org/jdk/pull/23034/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23034&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347427
  Stats: 33 lines in 1 file changed: 30 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/23034.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23034/head:pull/23034

PR: https://git.openjdk.org/jdk/pull/23034