With the 1.5.5 and 1.6.2 release-candidates it was discovered that files generated during the build are not covered by the apache-rat-plugin license-header check.
As a result the first compilation succeeds but a subsequent one may fail.
This is a bit surprising considering that the plugin is executed in the verify phase, which is executed after the compilation and execution of tests.
This is because the plugin is only run in the flink-parent project before anything is compiled. The plugin-configuration is explicitly disables inheritance.
I'm re-purposing this Jira to add the avro classes to the exclusion list.
However, in the long term I'd suggest to enable inheritance for the plugin and define the module-specific exclusions in each module respectively. This will allows to run the plugin in the verify phase of each module which would've caught this error.