Polish "Ensure indexer gracefully handle missing meta annotations"

Closes gh-22385

spring-context-indexer/src/main/java/org/springframework/context/index/processor/TypeHelper.java

@@ -114,7 +114,8 @@ class TypeHelper {
 		try {
 			return this.env.getElementUtils().getAllAnnotationMirrors(e);
 		}
-		catch (Throwable ex) {
+		catch (Exception ex) {
+			// This may fail if one of the annotation is not available
 			return Collections.emptyList();
 		}
 	}

spring-context-indexer/src/test/java/org/springframework/context/index/sample/cdi/SampleTransactional.java

@@ -19,9 +19,12 @@ package org.springframework.context.index.sample.cdi;
 import javax.transaction.Transactional;
 
 /**
- * Test candidate for {@link Transactional}.
+ * Test candidate for {@link Transactional}. This verifies that the annotation processor
+ * can process an annotation that declares itself an annotation that is not on the
+ * classpath.
  *
  * @author Vedran Pavic
+ * @author Stephane Nicoll
  */
 @Transactional
 public class SampleTransactional {