Handle bind exceptions in management context

This commit updates the logic for handling binding exceptions in the
management context when it is separate from the application context.
The changes allow the exception details to be visible to
DefaultErrorAttributes without causing the servlet container to
detect an error condition.

Fixes gh-21036

Author: scottfrederick

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/web/servlet/CompositeHandlerExceptionResolver.java

@@ -25,6 +25,7 @@
 
 import org.springframework.beans.factory.ListableBeanFactory;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.web.servlet.error.DefaultErrorAttributes;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
 import org.springframework.web.servlet.HandlerExceptionResolver;
 import org.springframework.web.servlet.ModelAndView;
@@ -51,13 +52,8 @@ public ModelAndView resolveException(HttpServletRequest request, HttpServletResp
 		if (this.resolvers == null) {
 			this.resolvers = extractResolvers();
 		}
-		ModelAndView resolved = this.resolvers.stream()
-				.map((resolver) -> resolver.resolveException(request, response, handler, ex)).filter(Objects::nonNull)
-				.findFirst().orElse(null);
-		if (resolved != null && resolved.isEmpty()) {
-			request.setAttribute("javax.servlet.error.exception", ex);
-		}
-		return resolved;
+		return this.resolvers.stream().map((resolver) -> resolver.resolveException(request, response, handler, ex))
+				.filter(Objects::nonNull).findFirst().orElse(null);
 	}
 
 	private List<HandlerExceptionResolver> extractResolvers() {
@@ -66,6 +62,7 @@ private List<HandlerExceptionResolver> extractResolvers() {
 		list.remove(this);
 		AnnotationAwareOrderComparator.sort(list);
 		if (list.isEmpty()) {
+			list.add(new DefaultErrorAttributes());
 			list.add(new DefaultHandlerExceptionResolver());
 		}
 		return list;

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/web/servlet/CompositeHandlerExceptionResolverTests.java

@@ -67,7 +67,6 @@ void resolverShouldAddDefaultResolverIfNonePresent() {
 		ModelAndView resolved = resolver.resolveException(this.request, this.response, null, exception);
 		assertThat(resolved).isNotNull();
 		assertThat(resolved.isEmpty()).isTrue();
-		assertThat(this.request.getAttribute("javax.servlet.error.exception")).isSameAs(exception);
 	}
 
 	private void load(Class<?>... configs) {