Since 7.10.0-alpha5, the Camunda BPM release job runs on JDK8. JDK8 introduces stricter formatting rules for the Javadoc and Camunda's projects are not consistent with these new rules. In order to prevent build failures, additional properties need to be added in all of the root pom.xml files of the Camunva projects (as in the camunda-external-task-client-java project):

<!-- disable javadoc linter for JDK8 to not fail on incomplete javadoc -->
<maven.javadoc.failOnError>false</maven.javadoc.failOnError>
<additionalparam>-Xdoclint:none</additionalparam>