RFR: 8365044: Missing copyright header in Contextual.java

[Dmitry Cherepanov]

Adding missing copyright header to Contextual.java

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Commit messages:
 - 8365044: Missing copyright header in Contextual.java

Changes: https://git.openjdk.org/jdk/pull/26693/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26693&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8365044
  Stats: 25 lines in 1 file changed: 25 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/26693.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26693/head:pull/26693

PR: https://git.openjdk.org/jdk/pull/26693