Configure CheckStyle rule for empty catch blocks

This commit configures a new CheckStyle rule that fails for empty
"catch" blocks, unless the exception is named "ignored" or "expected".

This also fixes the remaining instances missed by the previous commit.

Closes gh-35047

Author: bclozel

spring-aop/src/main/java/org/springframework/aop/aspectj/AspectJExpressionPointcut.java

@@ -453,9 +453,9 @@ private ShadowMatch getTargetShadowMatch(Method method, Class<?> targetClass) {
 							ClassUtils.toClassArray(ifcs), targetClass.getClassLoader());
 					targetMethod = ClassUtils.getMostSpecificMethod(targetMethod, compositeInterface);
 				}
-				// Implemented interfaces probably expose conflicting method signatures...
-				// Proceed with original target method.
-				catch (IllegalArgumentException ignored) {
+				catch (IllegalArgumentException ex) {
+					// Implemented interfaces probably expose conflicting method signatures...
+					// Proceed with original target method.
 				}
 			}
 		}
@@ -478,7 +478,7 @@ private ShadowMatch getShadowMatch(Method targetMethod, Method originalMethod) {
 					try {
 						shadowMatch = pointcutExpression.matchesMethodExecution(methodToMatch);
 					}
-					catch (ReflectionWorldException ignored) {
+					catch (ReflectionWorldException ex) {
 						// Failed to introspect target method, probably because it has been loaded
 						// in a special ClassLoader. Let's try the declaring ClassLoader instead...
 						try {
@@ -501,7 +501,7 @@ private ShadowMatch getShadowMatch(Method targetMethod, Method originalMethod) {
 						try {
 							shadowMatch = pointcutExpression.matchesMethodExecution(methodToMatch);
 						}
-						catch (ReflectionWorldException ignored) {
+						catch (ReflectionWorldException ex) {
 							// Could neither introspect the target class nor the proxy class ->
 							// let's try the original method's declaring class before we give up...
 							try {

spring-core/src/main/java/org/springframework/aot/nativex/substitution/Target_Introspector.java

@@ -48,7 +48,7 @@ private static Class<?> findCustomizerClass(Class<?> type) {
 				} while (!c.getName().equals("java.lang.Object"));
 			}
 		}
-		catch (Exception exception) {
+		catch (Exception ignored) {
 		}
 		return null;
 	}

spring-core/src/main/java/org/springframework/cglib/proxy/BridgeMethodResolver.java

@@ -73,8 +73,7 @@ public BridgeMethodResolver(Map declToBridge, ClassLoader classLoader) {
                 } finally {
                     is.close();
                 }
-            } catch (IOException ignored) {
-			}
+            } catch (IOException ignored) {}
         }
         return resolved;
     }

spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteProcessor.java

@@ -439,7 +439,8 @@ public <T> void onNext(AbstractListenerWriteProcessor<T> processor, T data) {
 				// ignore
 			}
 			@Override
-			public <T> void onError(AbstractListenerWriteProcessor<T> processor, Throwable ignored) {
+			public <T> void onError(AbstractListenerWriteProcessor<T> processor, Throwable ex) {
+				// ignore
 			}
 			@Override
 			public <T> void onComplete(AbstractListenerWriteProcessor<T> processor) {

spring-web/src/main/java/org/springframework/web/filter/FormContentFilter.java

@@ -116,7 +116,7 @@ private boolean shouldParse(HttpServletRequest request) {
 				MediaType mediaType = MediaType.parseMediaType(contentType);
 				return MediaType.APPLICATION_FORM_URLENCODED.includes(mediaType);
 			}
-			catch (IllegalArgumentException ex) {
+			catch (IllegalArgumentException ignored) {
 			}
 		}
 		return false;

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ExceptionHandlerExceptionResolverTests.java

@@ -611,7 +611,8 @@ static class ResponseStatusTestExceptionResolver {
 
 		@ExceptionHandler(SocketTimeoutException.class)
 		@ResponseStatus(code = HttpStatus.GATEWAY_TIMEOUT, reason = "gateway.timeout")
-		public void handleException(SocketTimeoutException ignored) {
+		public void handleException(SocketTimeoutException ex) {
+
 		}
 	}
 

src/checkstyle/checkstyle-suppressions.xml

@@ -9,7 +9,7 @@
 	<suppress files="(^(?!.+[\\/]src[\\/]main[\\/]java[\\/]).*)|(.*framework-docs.*)" checks="JavadocPackage" />
 
 	<!-- Global: tests and test fixtures -->
-	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/](java|java21)[\\/]" checks="AnnotationLocation|AnnotationUseStyle|AtclauseOrder|AvoidNestedBlocks|FinalClass|HideUtilityClassConstructor|InnerTypeLast|JavadocStyle|JavadocType|JavadocVariable|LeftCurly|MultipleVariableDeclarations|NeedBraces|OneTopLevelClass|OuterTypeFilename|RequireThis|SpringCatch|SpringJavadoc|SpringNoThis|SpringDeprecatedCheck"/>
+	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/](java|java21)[\\/]" checks="AnnotationLocation|AnnotationUseStyle|AtclauseOrder|AvoidNestedBlocks|FinalClass|HideUtilityClassConstructor|InnerTypeLast|JavadocStyle|JavadocType|JavadocVariable|LeftCurly|MultipleVariableDeclarations|NeedBraces|OneTopLevelClass|OuterTypeFilename|RequireThis|SpringCatch|SpringJavadoc|SpringNoThis|SpringDeprecatedCheck|EmptyCatchBlock"/>
 	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/](java|java21)[\\/]" checks="RegexpSinglelineJava" id="systemOutErrPrint"/>
 	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/](java|java21)[\\/]" checks="SpringJUnit5" message="should not be public"/>
 	<suppress files="[\\/]src[\\/]test[\\/](java|java21)[\\/]org[\\/]springframework[\\/].+(Tests|Suite)" checks="IllegalImport" id="bannedJUnitJupiterImports"/>

src/checkstyle/checkstyle.xml

@@ -39,6 +39,9 @@
 		</module>
 		<module name="com.puppycrawl.tools.checkstyle.checks.blocks.NeedBracesCheck"/>
 		<module name="com.puppycrawl.tools.checkstyle.checks.blocks.AvoidNestedBlocksCheck"/>
+		<module name="com.puppycrawl.tools.checkstyle.checks.blocks.EmptyCatchBlockCheck">
+			<property name="exceptionVariableName" value="expected|ignore"/>
+		</module>
 
 		<!-- Class Design -->
 		<module name="com.puppycrawl.tools.checkstyle.checks.design.FinalClassCheck"/>