Thanks. Have you got any example issues that are public on GitHub or something? I can't imagine changes in byte-code parsing for example that you'd hit if you were following the spec from the start.
e.g. the validation of invokeinterface changed at some point in ways that broke common tools, if I recall correctly. I don't have bug links to hand right now. The JVM previously accepted something that it was later changed to reject. This often happens including in cases where it doesn't matter. See the Java 17 release notes about the change to validation of agentmain entry points for an example of the sort of thing that is done constantly, even where it isn't actually required by any other change.
People don't execute specs, they execute implementations. In the end whether something is or is not fully compliant with the spec doesn't change the costs involved in fixing it.
People don't execute specs, they execute implementations. In the end whether something is or is not fully compliant with the spec doesn't change the costs involved in fixing it.