According to current AvroGenerated documentation
All Avro generated classes will be annotated with this annotation.
However, the nested Builder class that the specific Avro compiler generates does not get annotated with AvroGenerated or any user specified javaAnnotations. The Builder template is missing annotation generation as can be seen in the template file on Github
This has implications for tools relying on Generated annotations, such as test coverage tools like JaCoCo, which can ignore the generated SpecificRecord class but not the nested SpecificBuilder class as a result. Here is one JaCoCo bug describing the issue.