Build failure in Jenkins build of log4j/master (21)

[Apache Jenkins Server]

There is a build failure in log4j/master.

Build: https://builds.apache.org/job/log4j/job/master/21/
Logs: https://builds.apache.org/job/log4j/job/master/21/console
Changes: https://builds.apache.org/job/log4j/job/master/21/changes

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Mr. Jenkins