NPE Comparing alternative priorities

[ebullient]

Describe the bug
Beans.compareAlternativeBeans always prefers the value of the declaring bean, even if the declaring bean doesn't have an alternative priority and the bean itself does. This leads to an NPE when comparing alternate priorities.

Expected behavior
I expect something like this to work be resolvable (not sure this exactly reproduces.. I'm working on it)

    @Dependent
    static class NoParentAlternativePriority {

        @Produces
        @ApplicationScoped
        @AlternativePriority(3)
        PrioritizedProducerMethodBean bar = new PrioritizedProducerMethodBean();

        @Produces
        @ApplicationScoped
        @AlternativePriority(4)
        public PrioritizedProducerMethodBean createBar() {
            return new PrioritizedProducerMethodBean();
        }
    }

Actual behavior
As it happened in my situation, the comparison resulted in an NPE:

java.lang.RuntimeException: 
java.lang.RuntimeException: io.quarkus.builder.BuildException: Build failure: Build failed due to errors
        [error]: Build step io.quarkus.arc.deployment.ArcProcessor#validate threw an exception: java.lang.NullPointerException
        at io.quarkus.arc.processor.Beans.compareAlternativeBeans(Beans.java:551)
        at java.base/java.util.TimSort.countRunAndMakeAscending(TimSort.java:355)
        at java.base/java.util.TimSort.sort(TimSort.java:220)
        at java.base/java.util.Arrays.sort(Arrays.java:1515)
        at java.base/java.util.ArrayList.sort(ArrayList.java:1749)
        at io.quarkus.arc.processor.Beans.resolveAmbiguity(Beans.java:523)
        at io.quarkus.arc.processor.Beans.resolveInjectionPoint(Beans.java:475)
        at io.quarkus.arc.processor.BeanInfo.init(BeanInfo.java:420)
        at io.quarkus.arc.processor.BeanDeployment.init(BeanDeployment.java:224)
        at io.quarkus.arc.processor.BeanProcessor.initialize(BeanProcessor.java:130)
        at io.quarkus.arc.deployment.ArcProcessor.validate(ArcProcessor.java:291)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at io.quarkus.deployment.ExtensionLoader$2.execute(ExtensionLoader.java:938)
        at io.quarkus.builder.BuildContext.run(BuildContext.java:273)
        at org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
        at org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:2027)
        at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1551)
        at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1442)
        at java.base/java.lang.Thread.run(Thread.java:834)
        at org.jboss.threads.JBossThread.run(JBossThread.java:479)

Will create a PR to fix the problem that includes a reproducing test.

[ebullient]

To test the fix (in addition to UT).

1. Build all the Quarkus things
2. Extract the 8895 branch of the quarkus micrometer extension:
   https://github.com/ebullient/quarkus-micrometer-extension/tree/8895
3. Build and run one of the tests which will fail with the above NPE without the fix:
   mvn test "-Dtest=AlternativePriorityAnnotationTest" -DfailIfNoTests=false test

[mkouba]

Thanks for spotting this!

I think that the fix is not entirely correct. Beans.compareAlternativeBeans()should prefer the priority value of the producer method.

[ebullient]

As discussed, I preserved the original behavior, which I thought was wonky, too. It's all fixed now. ;)