Use @Singleton again

[SentryMan]

• uses @component only if Avaje is on the classpath
• uses Jakarta/javax @singleton depending on classpath
• uses Jakarta @singleton by default if both jakarta and javax on classpath
• adds a compiler arg to force javax

[rbygrave]

Yeah, I don't think this is the best approach. We ideally have 4 cases to support.

• using avaje-inject Jakarta (ignoring javax)
• using avaje-inject javax (ignoring Jakarta)
• using some other DI via Jakarta
• using some other DI via javax

As an alternative approach, it can detect avaje-inject and then failing that detect Jakarta or javax.

[SentryMan]

I can easily add the avaje detection and use @component for cases 1 and 2. But for scenarios 3 and 4, I think defaulting to jakarta unless specified is the way to go. Consider the scenario where javax/jakarta just happens to be on the classpath because of a transitive dependency. How should the processor proceed? A flag makes it simple.

[SentryMan]

@rbygrave how about this?

Will use avaje if it's there. Otherwise will use either jakarta/javax on the classpath. If both are on the classpath, will default to jakarta, unless overridden by the flag.

[rbygrave]

Yup, excellent.