If you see the error below then you need to remove use of maven-scr-plugin and convert all OSGi annotations to OSGi R6 annotations. For instructions, see here.
[main] [ERROR] Failed to execute goal org.apache.felix:maven-scr-plugin:1.26.4:scr (generate-scr-scrdescriptor) on project helloworld.core: /build_root/build/testsite/src/main/java/com/adobe/HelloWorldServiceImpl.java : Unable to load compiled class: com.adobe.HelloWorldServiceImpl: com/adobe/HelloWorldServiceImpl has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0 -> [Help 1]
For cloud manager builds the maven enforcer plugin fails with error "[main] [WARNING] Rule 1: org.apache.maven.plugins.enforcer.RequireJavaVersion". This is a known issue due to cloud manager using a different version of java to run the maven command versus compiling code. For now, omit requireJavaVersion from your maven-enforcer-plugin configurations.