Introduce MergedAnnotation finder methods

[philwebb]

Code to locate methods on classes based on annotations currently mostly uses a combination of MethodIntrospector and AnnotatedElementUtils.

For example, in EventListenerMethodProcessor:

spring-framework/spring-context/src/main/java/org/springframework/context/event/EventListenerMethodProcessor.java

Lines 148 to 150 in 6266370

	annotatedMethods = MethodIntrospector.selectMethods(targetType,
	(MethodIntrospector.MetadataLookup<EventListener>) method ->
	AnnotatedElementUtils.findMergedAnnotation(method, EventListener.class));

With the addition of the new MergedAnnotations API along with the annotation index work it might be nicer if we had a first class way to find such methods.

One possible solution would be to add finder methods to MergedAnnotation.

For example:

MergedAnnotation.find(SomeAnnotation.class).onMethodsIn(SomeCandidate.class);

[andresetevejob]

I do not know what I have to do, I link the exchanges and I wanted to know how to start to contribute to the code, should I read the source code how it goes. I have never participated in a opensource project, help me

[snicoll]

@andresetevejob thanks for offering to help. Newcomers should watch flagged issues with "help wanted" or "ideal for contribution". This issue isn't one of those. In particular, please don't consider assigned issues for which work might have started leading to duplicate efforts.

The Spring Boot project has dedicated issues for newcomers, see the first timers only label. We have two opened at the moment and they're both assigned so please watch out that link for more.

[andresetevejob]

Thanks you, Nicoll Le jeu. 14 mars 2019 à 09:26, Stéphane Nicoll <notifications@github.com> a écrit :

…

@andresetevejob <https://github.com/andresetevejob> thanks for offering to help. Newcomers should watch flagged issues with "help wanted" or "ideal for contribution". This issue isn't one of those. In particular, please don't consider assigned issues for which work might have started leading to duplicate efforts. The Spring Boot project has dedicated issues for newcomers, see [ https://github.com/spring-projects/spring-boot/labels/status%3A%20first-timers-only](the <https://github.com/spring-projects/spring-boot/labels/status%3A%20first-timers-only%5D(the> first timers only label). We have two opened at the moment and they're both assigned so please watch out that link for more. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#22569 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ADL-9OjiCla5aGeyPJS_Tg53trwtzcsZks5vWgesgaJpZM4bpvWc> .

[sbrannen]

Team Decision: features like MethodIntrospector and MergedAnnotations are orthogonal concerns and should therefore not be combined in a common API/implementation.