Rename exception variables in empty catch blocks

The Spring codebase sometimes ignores exceptions in catch blocks on
purpose. This is often called out by an inline comment.
We should make this more obvious by renaming the exception argument in
the catch block to declare whether the exception is "ignored" or
"expected".

See gh-35047

Signed-off-by: Vincent Potucek <vpotucek@me.com>
[brian.clozel@broadcom.com: rework commit message]
Signed-off-by: Brian Clozel <brian.clozel@broadcom.com>

integration-tests/src/test/java/org/springframework/aop/framework/autoproxy/AdvisorAutoProxyCreatorIntegrationTests.java

@@ -158,8 +158,7 @@ class AdvisorAutoProxyCreatorIntegrationTests {
 		try {
 			rb.echoException(new ServletException());
 		}
-		catch (ServletException ex) {
+		catch (ServletException ignored) {
-
 		}
 		assertThat(txMan.commits).as("Transaction counts match").isEqualTo(1);
 	}
@@ -272,7 +271,7 @@ class OrderedTxCheckAdvisor extends StaticMethodMatcherPointcutAdvisor implement
 					TransactionInterceptor.currentTransactionStatus();
 					throw new RuntimeException("Shouldn't have a transaction");
 				}
-				catch (NoTransactionException ex) {
+				catch (NoTransactionException ignored) {
 					// this is Ok
 				}
 			}

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

@@ -453,9 +453,9 @@ public class AspectJExpressionPointcut extends AbstractExpressionPointcut
 							ClassUtils.toClassArray(ifcs), targetClass.getClassLoader());
 					targetMethod = ClassUtils.getMostSpecificMethod(targetMethod, compositeInterface);
 				}
-				catch (IllegalArgumentException ex) {
+				// Implemented interfaces probably expose conflicting method signatures...
-					// Implemented interfaces probably expose conflicting method signatures...
+				// Proceed with original target method.
-					// Proceed with original target method.
+				catch (IllegalArgumentException ignored) {
 				}
 			}
 		}
@@ -478,7 +478,7 @@ public class AspectJExpressionPointcut extends AbstractExpressionPointcut
 					try {
 						shadowMatch = pointcutExpression.matchesMethodExecution(methodToMatch);
 					}
-					catch (ReflectionWorldException ex) {
+					catch (ReflectionWorldException ignored) {
 						// 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 @@ public class AspectJExpressionPointcut extends AbstractExpressionPointcut
 						try {
 							shadowMatch = pointcutExpression.matchesMethodExecution(methodToMatch);
 						}
-						catch (ReflectionWorldException ex) {
+						catch (ReflectionWorldException ignored) {
 							// 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-beans/src/main/java/org/springframework/beans/factory/annotation/BeanFactoryAnnotationUtils.java

@@ -208,8 +208,8 @@ public abstract class BeanFactoryAnnotationUtils {
 					}
 				}
 			}
-			catch (NoSuchBeanDefinitionException ex) {
+			catch (NoSuchBeanDefinitionException ignored) {
-				// Ignore - can't compare qualifiers for a manually registered singleton object
+				// can't compare qualifiers for a manually registered singleton object
 			}
 		}
 		return false;

spring-context/src/main/java/org/springframework/context/support/PostProcessorRegistrationDelegate.java

@@ -523,8 +523,7 @@ final class PostProcessorRegistrationDelegate {
 			try {
 				typedStringValue.resolveTargetType(this.beanFactory.getBeanClassLoader());
 			}
-			catch (ClassNotFoundException ex) {
+			catch (ClassNotFoundException ignored) {
-				// ignore
 			}
 		}
 

spring-context/src/main/java/org/springframework/validation/beanvalidation/LocalValidatorFactoryBean.java

@@ -266,8 +266,8 @@ public class LocalValidatorFactoryBean extends SpringValidatorAdapter
 				Method eclMethod = configuration.getClass().getMethod("externalClassLoader", ClassLoader.class);
 				ReflectionUtils.invokeMethod(eclMethod, configuration, this.applicationContext.getClassLoader());
 			}
-			catch (NoSuchMethodException ex) {
+			catch (NoSuchMethodException ignored) {
-				// Ignore - no Hibernate Validator 5.2+ or similar provider
+				// no Hibernate Validator 5.2+ or similar provider
 			}
 		}
 
@@ -417,8 +417,8 @@ public class LocalValidatorFactoryBean extends SpringValidatorAdapter
 			try {
 				return super.unwrap(type);
 			}
-			catch (ValidationException ex) {
+			catch (ValidationException ignored) {
-				// Ignore - we'll try ValidatorFactory unwrapping next
+				// we'll try ValidatorFactory unwrapping next
 			}
 		}
 		if (this.validatorFactory != null) {

spring-context/src/test/java/org/springframework/aop/framework/AbstractAopProxyTests.java

@@ -233,8 +233,7 @@ abstract class AbstractAopProxyTests {
 		try {
 			p2.echo(new IOException());
 		}
-		catch (IOException ex) {
+		catch (IOException ignored) {
-
 		}
 		assertThat(cta.getCalls()).isEqualTo(2);
 	}

spring-core-test/src/main/java/org/springframework/core/test/tools/CompileWithForkedClassLoaderClassLoader.java

@@ -84,8 +84,7 @@ final class CompileWithForkedClassLoaderClassLoader extends ClassLoader {
 			try (stream) {
 				return stream.readAllBytes();
 			}
-			catch (IOException ex) {
+			catch (IOException ignored) {
-				// ignore
 			}
 		}
 		return null;

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

@@ -73,7 +73,8 @@ class BridgeMethodResolver {
                 } finally {
                     is.close();
                 }
-            } catch (IOException ignored) {}
+            } catch (IOException ignored) {
+			}
         }
         return resolved;
     }

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

@@ -62,8 +62,8 @@ public class MethodProxy {
 			try {
 				proxy.init();
 			}
-			catch (CodeGenerationException ex) {
+			catch (CodeGenerationException ignored) {
-				// Ignore - to be retried when actually needed later on (possibly not at all)
+				// to be retried when actually needed later on (possibly not at all)
 			}
 		}
 		// SPRING PATCH END

spring-core/src/main/java/org/springframework/core/io/support/SpringFactoriesLoader.java

@@ -438,8 +438,7 @@ public class SpringFactoriesLoader {
 					return constructor;
 				}
 			}
-			catch (UnsupportedOperationException ex) {
+			catch (UnsupportedOperationException ignored) {
-				// ignore
 			}
 			return null;
 		}

spring-core/src/main/java/org/springframework/util/FileCopyUtils.java

@@ -229,8 +229,7 @@ public abstract class FileCopyUtils {
 		try {
 			closeable.close();
 		}
-		catch (IOException ex) {
+		catch (IOException ignored) {
-			// ignore
 		}
 	}
 

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/DefaultStompSession.java

@@ -526,8 +526,7 @@ public class DefaultStompSession implements ConnectionHandlingStompSession {
 			try {
 				conn.close();
 			}
-			catch (Throwable ex) {
+			catch (Throwable ignored) {
-				// ignore
 			}
 		}
 	}

spring-oxm/src/main/java/org/springframework/oxm/jaxb/Jaxb2Marshaller.java

@@ -1000,8 +1000,7 @@ public class Jaxb2Marshaller implements MimeMarshaller, MimeUnmarshaller, Generi
 				URI uri = ResourceUtils.toURI(elementNamespace);
 				return uri.getHost();
 			}
-			catch (URISyntaxException ex) {
+			catch (URISyntaxException ignored) {
-				// ignore
 			}
 			return dataHandler.getName();
 		}

spring-r2dbc/src/test/java/org/springframework/r2dbc/connection/R2dbcTransactionManagerTests.java

@@ -710,8 +710,7 @@ class R2dbcTransactionManagerTests {
 			try {
 				return Mono.fromRunnable(() -> doAfterCompletion(status));
 			}
-			catch (Throwable ex) {
+			catch (Throwable ignored) {
-				// ignore
 			}
 
 			return Mono.empty();

spring-test/src/main/java/org/springframework/mock/http/client/MockClientHttpResponse.java

@@ -100,8 +100,7 @@ public class MockClientHttpResponse extends MockHttpInputMessage implements Clie
 		try {
 			getBody().close();
 		}
-		catch (IOException ex) {
+		catch (IOException ignored) {
-			// ignore
 		}
 	}
 

spring-test/src/main/java/org/springframework/mock/web/MockHttpServletRequest.java

@@ -1129,8 +1129,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 			try {
 				return simpleDateFormat.parse(value).getTime();
 			}
-			catch (ParseException ex) {
+			catch (ParseException ignored) {
-				// ignore
 			}
 		}
 		throw new IllegalArgumentException("Cannot parse date value '" + value + "' for '" + name + "' header");

spring-web/src/main/java/org/springframework/http/HttpHeaders.java

@@ -1223,8 +1223,7 @@ public class HttpHeaders implements Serializable {
 			try {
 				port = Integer.parseInt(portString);
 			}
-			catch (NumberFormatException ex) {
+			catch (NumberFormatException ignored) {
-				// ignore
 			}
 		}
 

spring-web/src/main/java/org/springframework/http/client/HttpComponentsClientHttpResponse.java

@@ -89,8 +89,7 @@ final class HttpComponentsClientHttpResponse implements ClientHttpResponse {
 				this.httpResponse.close();
 			}
 		}
-		catch (IOException ex) {
+		catch (IOException ignored) {
-			// Ignore exception on close...
 		}
 	}
 

spring-web/src/main/java/org/springframework/http/client/ReactorClientHttpResponse.java

@@ -108,8 +108,7 @@ final class ReactorClientHttpResponse implements ClientHttpResponse {
 			StreamUtils.drain(body);
 			body.close();
 		}
-		catch (IOException ex) {
+		catch (IOException ignored) {
-			// ignore
 		}
 	}
 

spring-web/src/main/java/org/springframework/http/client/reactive/HttpComponentsClientHttpResponse.java

@@ -119,8 +119,7 @@ class HttpComponentsClientHttpResponse extends AbstractClientHttpResponse {
 				ZonedDateTime expiresDate = ZonedDateTime.parse(expiresAttribute, DateTimeFormatter.RFC_1123_DATE_TIME);
 				return Duration.between(ZonedDateTime.now(expiresDate.getZone()), expiresDate).toSeconds();
 			}
-			catch (DateTimeParseException ex) {
+			catch (DateTimeParseException ignored) {
-				// ignore
 			}
 		}
 		return -1;

spring-web/src/main/java/org/springframework/http/converter/ResourceHttpMessageConverter.java

@@ -158,20 +158,20 @@ public class ResourceHttpMessageConverter extends AbstractHttpMessageConverter<R
 				in.transferTo(out);
 				out.flush();
 			}
-			catch (NullPointerException ex) {
+			catch (NullPointerException ignored) {
-				// ignore, see SPR-13620
+				// see SPR-13620
 			}
 			finally {
 				try {
 					in.close();
 				}
-				catch (Throwable ex) {
+				catch (Throwable ignored) {
-					// ignore, see SPR-12999
+					// see SPR-12999
 				}
 			}
 		}
-		catch (FileNotFoundException ex) {
+		catch (FileNotFoundException ignored) {
-			// ignore, see SPR-12999
+			// see SPR-12999
 		}
 	}
 

spring-web/src/main/java/org/springframework/http/converter/ResourceRegionHttpMessageConverter.java

@@ -183,8 +183,7 @@ public class ResourceRegionHttpMessageConverter extends AbstractGenericHttpMessa
 			try {
 				in.close();
 			}
-			catch (IOException ex) {
+			catch (IOException ignored) {
-				// ignore
 			}
 		}
 	}
@@ -244,8 +243,7 @@ public class ResourceRegionHttpMessageConverter extends AbstractGenericHttpMessa
 					in.close();
 				}
 			}
-			catch (IOException ex) {
+			catch (IOException ignored) {
-				// ignore
 			}
 		}
 

spring-web/src/main/java/org/springframework/http/converter/xml/SourceHttpMessageConverter.java

@@ -270,8 +270,7 @@ public class SourceHttpMessageConverter<T extends Source> extends AbstractHttpMe
 				transform(t, new StreamResult(os));
 				return os.count;
 			}
-			catch (TransformerException ex) {
+			catch (TransformerException ignored) {
-				// ignore
 			}
 		}
 		return null;

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

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

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

@@ -309,8 +309,7 @@ public class ServletHttpHandlerAdapter implements Servlet {
 			try {
 				listener.onTimeout(event);
 			}
-			catch (Exception ex) {
+			catch (Exception ignored) {
-				// Ignore
 			}
 		}
 
@@ -318,8 +317,7 @@ public class ServletHttpHandlerAdapter implements Servlet {
 			try {
 				listener.onError(event);
 			}
-			catch (Exception ex) {
+			catch (Exception ignored) {
-				// Ignore
 			}
 		}
 
@@ -327,8 +325,7 @@ public class ServletHttpHandlerAdapter implements Servlet {
 			try {
 				listener.onComplete(event);
 			}
-			catch (Exception ex) {
+			catch (Exception ignored) {
-				// Ignore
 			}
 		}
 

spring-web/src/main/java/org/springframework/web/client/HttpMessageConverterExtractor.java

@@ -152,8 +152,7 @@ public class HttpMessageConverterExtractor<T> implements ResponseExtractor<T> {
 		try {
 			return FileCopyUtils.copyToByteArray(response.getBody());
 		}
-		catch (IOException ex) {
+		catch (IOException ignored) {
-			// ignore
 		}
 		return new byte[0];
 	}

spring-web/src/main/java/org/springframework/web/context/request/async/CallableInterceptorChain.java

@@ -113,8 +113,7 @@ class CallableInterceptorChain {
 			try {
 				future.cancel(true);
 			}
-			catch (Throwable ex) {
+			catch (Throwable ignored) {
-				// Ignore
 			}
 		}
 	}

spring-web/src/main/java/org/springframework/web/context/request/async/StandardServletAsyncWebRequest.java

@@ -235,8 +235,7 @@ public class StandardServletAsyncWebRequest extends ServletWebRequest implements
 					break;
 				}
 			}
-			catch (InterruptedException ex) {
+			catch (InterruptedException ignored) {
-				// ignore
 			}
 		}
 

spring-web/src/main/java/org/springframework/web/context/support/ServletContextResource.java

@@ -122,8 +122,7 @@ public class ServletContextResource extends AbstractFileResolvingResource implem
 			try {
 				is.close();
 			}
-			catch (IOException ex) {
+			catch (IOException ignored) {
-				// ignore
 			}
 			return true;
 		}

spring-web/src/main/java/org/springframework/web/service/registry/HttpServiceProxyRegistryFactoryBean.java

@@ -151,8 +151,7 @@ public final class HttpServiceProxyRegistryFactoryBean
 				Class<?> clazz = ClassUtils.forName(className, HttpServiceGroupAdapter.class.getClassLoader());
 				groupAdapters.put(clientType, (HttpServiceGroupAdapter<?>) BeanUtils.instantiateClass(clazz));
 			}
-			catch (ClassNotFoundException ex) {
+			catch (ClassNotFoundException ignored) {
-				// ignore
 			}
 		}
 	}

spring-web/src/test/java/org/springframework/web/context/request/RequestContextListenerTests.java

@@ -93,7 +93,7 @@ class RequestContextListenerTests {
 		try {
 			thread.join();
 		}
-		catch (InterruptedException ex) {
+		catch (InterruptedException ignored) {
 		}
 		// Still bound to original thread, but at least completed.
 		assertThat(RequestContextHolder.getRequestAttributes()).isNotNull();

spring-web/src/testFixtures/java/org/springframework/web/testfixture/http/client/MockClientHttpResponse.java

@@ -100,8 +100,7 @@ public class MockClientHttpResponse extends MockHttpInputMessage implements Clie
 		try {
 			getBody().close();
 		}
-		catch (IOException ex) {
+		catch (IOException ignored) {
-			// ignore
 		}
 	}
 

spring-web/src/testFixtures/java/org/springframework/web/testfixture/servlet/MockHttpServletRequest.java

@@ -1128,8 +1128,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 			try {
 				return simpleDateFormat.parse(value).getTime();
 			}
-			catch (ParseException ex) {
+			catch (ParseException ignored) {
-				// ignore
 			}
 		}
 		throw new IllegalArgumentException("Cannot parse date value '" + value + "' for '" + name + "' header");

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/WebClientUtils.java

@@ -77,8 +77,7 @@ abstract class WebClientUtils {
 			try {
 				uri = new URI(uri.getScheme(), null, uri.getHost(), uri.getPort(), uri.getPath(), null, null);
 			}
-			catch (URISyntaxException ex) {
+			catch (URISyntaxException ignored) {
-				// ignore
 			}
 		}
 		return httpMethod.name() + " " + uri;

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/DefaultServerRequestBuilder.java

@@ -357,8 +357,7 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 							.cache();
 				}
 			}
-			catch (InvalidMediaTypeException ex) {
+			catch (InvalidMediaTypeException ignored) {
-				// Ignore
 			}
 			return EMPTY_FORM_DATA;
 		}
@@ -379,8 +378,7 @@ class DefaultServerRequestBuilder implements ServerRequest.Builder {
 							.cache();
 				}
 			}
-			catch (InvalidMediaTypeException ex) {
+			catch (InvalidMediaTypeException ignored) {
-				// Ignore
 			}
 			return EMPTY_MULTIPART_DATA;
 		}

spring-webflux/src/main/java/org/springframework/web/reactive/resource/ResourceHandlerUtils.java

@@ -76,8 +76,7 @@ public abstract class ResourceHandlerUtils {
 			Assert.isTrue(path.endsWith(FOLDER_SEPARATOR) || path.endsWith(WINDOWS_FOLDER_SEPARATOR),
 					"Resource location does not end with slash: " + path);
 		}
-		catch (IOException ex) {
+		catch (IOException ignored) {
-			// ignore
 		}
 	}
 

spring-webflux/src/main/java/org/springframework/web/reactive/result/condition/ProducesRequestCondition.java

@@ -211,8 +211,7 @@ public final class ProducesRequestCondition extends AbstractRequestCondition<Pro
 					return EMPTY_CONDITION;
 				}
 			}
-			catch (NotAcceptableStatusException | UnsupportedMediaTypeStatusException ex) {
+			catch (NotAcceptableStatusException | UnsupportedMediaTypeStatusException ignored) {
-				// Ignore
 			}
 		}
 		return null;

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilder.java

@@ -622,8 +622,7 @@ public class MvcUriComponentsBuilder {
 			try {
 				return wac.getBean(MVC_URI_COMPONENTS_CONTRIBUTOR_BEAN_NAME, CompositeUriComponentsContributor.class);
 			}
-			catch (NoSuchBeanDefinitionException ex) {
+			catch (NoSuchBeanDefinitionException ignored) {
-				// Ignore
 			}
 		}
 		return defaultUriComponentsContributor;

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapter.java

@@ -788,8 +788,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 				return getBeanFactory().getBean(
 						DispatcherServlet.LOCALE_RESOLVER_BEAN_NAME, LocaleResolver.class);
 			}
-			catch (NoSuchBeanDefinitionException ex) {
+			catch (NoSuchBeanDefinitionException ignored) {
-				// ignore
 			}
 		}
 		return null;

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestPartMethodArgumentResolver.java

@@ -191,8 +191,7 @@ public class RequestPartMethodArgumentResolver extends AbstractMessageConverterM
 		try {
 			body.close();
 		}
-		catch (IOException ex) {
+		catch (IOException ignored) {
-			// ignore
 		}
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/ResourceHandlerUtils.java

@@ -77,8 +77,7 @@ public abstract class ResourceHandlerUtils {
 			Assert.isTrue(path.endsWith(FOLDER_SEPARATOR) || path.endsWith(WINDOWS_FOLDER_SEPARATOR),
 					"Resource location does not end with slash: " + path);
 		}
-		catch (IOException ex) {
+		catch (IOException ignored) {
-			// ignore
 		}
 	}
 

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

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

spring-websocket/src/main/java/org/springframework/web/socket/handler/BinaryWebSocketHandler.java

@@ -41,8 +41,7 @@ public class BinaryWebSocketHandler extends AbstractWebSocketHandler {
 		try {
 			session.close(CloseStatus.NOT_ACCEPTABLE.withReason("Text messages not supported"));
 		}
-		catch (IOException ex) {
+		catch (IOException ignored) {
-			// ignore
 		}
 	}
 

spring-websocket/src/main/java/org/springframework/web/socket/handler/ExceptionWebSocketHandlerDecorator.java

@@ -93,8 +93,7 @@ public class ExceptionWebSocketHandlerDecorator extends WebSocketHandlerDecorato
 			try {
 				session.close(CloseStatus.SERVER_ERROR);
 			}
-			catch (Throwable ex) {
+			catch (Throwable ignored) {
-				// ignore
 			}
 		}
 	}

spring-websocket/src/main/java/org/springframework/web/socket/handler/TextWebSocketHandler.java

@@ -41,8 +41,7 @@ public class TextWebSocketHandler extends AbstractWebSocketHandler {
 		try {
 			session.close(CloseStatus.NOT_ACCEPTABLE.withReason("Binary messages not supported"));
 		}
-		catch (IOException ex) {
+		catch (IOException ignored) {
-			// ignore
 		}
 	}
 

spring-websocket/src/main/java/org/springframework/web/socket/messaging/StompSubProtocolHandler.java

@@ -412,8 +412,7 @@ public class StompSubProtocolHandler implements SubProtocolHandler, ApplicationE
 			try {
 				session.close(CloseStatus.PROTOCOL_ERROR);
 			}
-			catch (IOException ex) {
+			catch (IOException ignored) {
-				// Ignore
 			}
 		}
 	}