When I execute mvn package -T8, the following warning will be displayed:

[WARNING] *****************************************************************
[WARNING] * Your build is requesting parallel execution, but project *
[WARNING] * contains the following plugin(s) that are not marked as *
[WARNING] * @threadsafe to support parallel building. *
[WARNING] * While this /may/ work fine, please look for plugin updates *
[WARNING] * and/or request plugins be made thread-safe. *
[WARNING] * If reporting an issue, report it against the plugin in *
[WARNING] * question, not against maven-core *
[WARNING] *****************************************************************
[WARNING] The following plugins are not marked @threadsafe in XXX:
[WARNING] de.jflex:jflex-maven-plugin:1.6.1
[WARNING] *****************************************************************