This is Java / Gradle style check. You need to create package between your code (Java classes) and java folder so that the structure would looks like scr/main/java/packageName/YourCode.java NOT like scr/main/java/YourCode.java
9. Sep 2021 | Robert
All classes, interfaces, enums and annotations must belong to a named package
Possible issue with your Java (or Gradle) project structure