Scheduler - detect scheduled methods of the same name on a class

- fix #31547

Author: mkouba

extensions/scheduler/deployment/src/main/java/io/quarkus/scheduler/deployment/ScheduledBusinessMethodItem.java

@@ -48,4 +48,8 @@ public boolean isNonBlocking() {
         return nonBlocking;
     }
 
+    public String getMethodDescription() {
+        return method.declaringClass().name() + "#" + method.name() + "()";
+    }
+
 }

extensions/scheduler/deployment/src/main/java/io/quarkus/scheduler/deployment/SchedulerProcessor.java

@@ -12,9 +12,11 @@
 import java.time.ZoneId;
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionStage;
 import java.util.function.Function;
@@ -192,17 +194,23 @@ void validateScheduledBusinessMethods(SchedulerConfig config, List<ScheduledBusi
             ValidationPhaseBuildItem validationPhase, BuildProducer<ValidationErrorBuildItem> validationErrors) {
         List<Throwable> errors = new ArrayList<>();
         Map<String, AnnotationInstance> encounteredIdentities = new HashMap<>();
+        Set<String> methodDescriptions = new HashSet<>();
 
         for (ScheduledBusinessMethodItem scheduledMethod : scheduledMethods) {
+            if (!methodDescriptions.add(scheduledMethod.getMethodDescription())) {
+                errors.add(new IllegalStateException("Multiple @Scheduled methods of the same name declared on the same class: "
+                        + scheduledMethod.getMethodDescription()));
+                continue;
+            }
             MethodInfo method = scheduledMethod.getMethod();
             if (Modifier.isAbstract(method.flags())) {
                 errors.add(new IllegalStateException("@Scheduled method must not be abstract: "
-                        + method.declaringClass().name() + "#" + method.name() + "()"));
+                        + scheduledMethod.getMethodDescription()));
                 continue;
             }
             if (Modifier.isPrivate(method.flags())) {
                 errors.add(new IllegalStateException("@Scheduled method must not be private: "
-                        + method.declaringClass().name() + "#" + method.name() + "()"));
+                        + scheduledMethod.getMethodDescription()));
                 continue;
             }