What is the purpose for EclipseLink internal API classes to implement Serializable? Also, was there a reason they were not given default static serialVersionUIDs? For the core project, I notice the warning that should be displaying for this is configured to ignore. I imagine this default was intentionally changed, not only to turn off the warning but to indicate that static serialVersionUIDs were not desired for some reason. Is there a problem with implementing static serialVersionUIDs on eclipselink classes that implement java.io.Serializable? Since classes are currently using the generated ID, even compatible changes are changing the serializable IDs.