Jenkins job Celix/doxygen-docs#923 failed

[Jenkins]

There is a build failure in Celix/doxygen-docs.
Build: https://ci-builds.apache.org/job/Celix/job/doxygen-docs/923/
Logs: https://ci-builds.apache.org/job/Celix/job/doxygen-docs/923/console
Changes: https://ci-builds.apache.org/job/Celix/job/doxygen-docs/923/changes