Check for instanceof Throwable in AnnotationAttributes#assertNotException

Prior to this commit, AnnotationAttributes#assertNotException checked if
the attribute value was an instance of Exception. Although this was
typically sufficient, the scope was not always broad enough -- for
example, if AnnotationReadingVisitorUtils#convertClassValues stored a
Throwable in the map (such as a LinkageError).

This commit fixes this by checking for an instance of Throwable in
AnnotationAttributes#assertNotException.

Closes gh-23424

spring-core/src/main/java/org/springframework/core/annotation/AnnotationAttributes.java

@@ -353,10 +353,10 @@ public class AnnotationAttributes extends LinkedHashMap<String, Object> {
 	}
 
 	private void assertNotException(String attributeName, Object attributeValue) {
-		if (attributeValue instanceof Exception) {
+		if (attributeValue instanceof Throwable) {
 			throw new IllegalArgumentException(String.format(
 					"Attribute '%s' for annotation [%s] was not resolvable due to exception [%s]",
-					attributeName, this.displayName, attributeValue), (Exception) attributeValue);
+					attributeName, this.displayName, attributeValue), (Throwable) attributeValue);
 		}
 	}
 

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

@@ -77,13 +77,21 @@ public class AnnotationAttributesTests {
 	}
 
 	@Test
-	public void unresolvableClass() throws Exception {
+	public void unresolvableClassWithClassNotFoundException() throws Exception {
 		attributes.put("unresolvableClass", new ClassNotFoundException("myclass"));
 		exception.expect(IllegalArgumentException.class);
 		exception.expectMessage(containsString("myclass"));
 		attributes.getClass("unresolvableClass");
 	}
 
+	@Test
+	public void unresolvableClassWithLinkageError() throws Exception {
+		attributes.put("unresolvableClass", new LinkageError("myclass"));
+		exception.expect(IllegalArgumentException.class);
+		exception.expectMessage(containsString("myclass"));
+		attributes.getClass("unresolvableClass");
+	}
+
 	@Test
 	public void singleElementToSingleElementArrayConversionSupport() throws Exception {
 		Filter filter = FilteredClass.class.getAnnotation(Filter.class);