Fix bug in TYPE_HIERARCHY_AND_ENCLOSING_CLASSES strategy

Prior to this commit, the new `TYPE_HIERARCHY_AND_ENCLOSING_CLASSES`
annotation search strategy failed to find annotations on enclosing
classes if the source class was a nested class that itself had no
annotations present.

This commit fixes this by adding special logic to AnnotationsScanner's
isWithoutHierarchy() method to properly support nested classes.

Closes gh-23378

spring-core/src/test/java/org/springframework/core/annotation/MergedAnnotationsTests.java

@@ -692,6 +692,19 @@ public class MergedAnnotationsTests {
 				Transactional.class)).hasSize(1);
 	}
 
+	@Test
+	public void streamTypeHierarchyAndEnclosingClassesFromNonAnnotatedInnerClassWithAnnotatedEnclosingClass() {
+		Stream<Class<?>> classes = MergedAnnotations.from(AnnotatedClass.NonAnnotatedInnerClass.class,
+			SearchStrategy.TYPE_HIERARCHY_AND_ENCLOSING_CLASSES).stream().map(MergedAnnotation::getType);
+		assertThat(classes).containsExactly(Component.class, Indexed.class);
+	}
+
+	@Test
+	public void streamTypeHierarchyAndEnclosingClassesFromNonAnnotatedStaticNestedClassWithAnnotatedEnclosingClass() {
+		Stream<Class<?>> classes = MergedAnnotations.from(AnnotatedClass.NonAnnotatedStaticNestedClass.class,
+			SearchStrategy.TYPE_HIERARCHY_AND_ENCLOSING_CLASSES).stream().map(MergedAnnotation::getType);
+		assertThat(classes).containsExactly(Component.class, Indexed.class);
+	}
 	@Test
 	public void getFromMethodWithMethodAnnotationOnLeaf() throws Exception {
 		Method method = Leaf.class.getMethod("annotatedOnLeaf");
@@ -2112,6 +2125,16 @@ public class MergedAnnotationsTests {
 	static class NonAnnotatedClass {
 	}
 
+	@Component
+	static class AnnotatedClass {
+
+		class NonAnnotatedInnerClass {
+		}
+
+		static class NonAnnotatedStaticNestedClass {
+		}
+	}
+
 	static interface NonAnnotatedInterface {
 	}
 
@@ -2839,6 +2862,7 @@ public class MergedAnnotationsTests {
 	public static class ImplementsInterfaceWithGenericAnnotatedMethod
 			implements InterfaceWithGenericAnnotatedMethod<String> {
 
+		@Override
 		public void foo(String t) {
 		}
 	}
@@ -2852,6 +2876,7 @@ public class MergedAnnotationsTests {
 	public static class ExtendsBaseClassWithGenericAnnotatedMethod
 			extends BaseClassWithGenericAnnotatedMethod<String> {
 
+		@Override
 		public void foo(String t) {
 		}
 	}