Update @SourceStreams and @SinkStreams docs to clarify that they are required

[nicoweidner]

Resolves #45

[gunnarmorling]

LGTM. One additional thing we could do is raising a warning in the annotation processor which creates the META-INF file if there are no streams at all. While it's technically still valid (if a user doesn't want to connect to any Decodable streams at all), I think it should be the exceptional case. So more users would benefit from that build-time warning than would be irritated by a "false" warning. WDYT?

[nicoweidner]

LGTM. One additional thing we could do is raising a warning in the annotation processor which creates the META-INF file if there are no streams at all. While it's technically still valid (if a user doesn't want to connect to any Decodable streams at all), I think it should be the exceptional case. So more users would benefit from that build-time warning than would be irritated by a "false" warning. WDYT?

Ok, I tried to change the processor so it always runs and prints a warning when neither sources nor sinks are specified. It now processes all annotations so that it's not skipped entirely if the annotations are not present - but in turn, it doesn't mark the annotations as processed so other processors can process their annotations afterwards.

I also fixed a NPE I noticed by chance.

[nicoweidner]

@gunnarmorling quick ping

[gunnarmorling]

LGTM, thx!

[github-actions]

🎉 This issue has been resolved in v1.0.0.Beta3 (Release Notes)