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>

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) {
-				// ignore
+			catch (NumberFormatException ignored) {
 			}
 		}
 

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) {
-			// Ignore exception on close...
+		catch (IOException ignored) {
 		}
 	}
 

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) {
-			// ignore
+		catch (IOException ignored) {
 		}
 	}
 

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) {
-				// ignore
+			catch (DateTimeParseException ignored) {
 			}
 		}
 		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) {
-				// ignore, see SPR-13620
+			catch (NullPointerException ignored) {
+				// see SPR-13620
 			}
 			finally {
 				try {
 					in.close();
 				}
-				catch (Throwable ex) {
-					// ignore, see SPR-12999
+				catch (Throwable ignored) {
+					// see SPR-12999
 				}
 			}
 		}
-		catch (FileNotFoundException ex) {
-			// ignore, see SPR-12999
+		catch (FileNotFoundException ignored) {
+			// 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) {
-				// ignore
+			catch (IOException ignored) {
 			}
 		}
 	}
@@ -244,8 +243,7 @@ public class ResourceRegionHttpMessageConverter extends AbstractGenericHttpMessa
 					in.close();
 				}
 			}
-			catch (IOException ex) {
-				// ignore
+			catch (IOException ignored) {
 			}
 		}
 

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) {
-				// ignore
+			catch (TransformerException ignored) {
 			}
 		}
 		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) {
-				// ignore
+			public <T> void onError(AbstractListenerWriteProcessor<T> processor, Throwable ignored) {
 			}
 			@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) {
-				// Ignore
+			catch (Exception ignored) {
 			}
 		}
 
@@ -318,8 +317,7 @@ public class ServletHttpHandlerAdapter implements Servlet {
 			try {
 				listener.onError(event);
 			}
-			catch (Exception ex) {
-				// Ignore
+			catch (Exception ignored) {
 			}
 		}
 
@@ -327,8 +325,7 @@ public class ServletHttpHandlerAdapter implements Servlet {
 			try {
 				listener.onComplete(event);
 			}
-			catch (Exception ex) {
-				// Ignore
+			catch (Exception ignored) {
 			}
 		}
 

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) {
-			// ignore
+		catch (IOException ignored) {
 		}
 		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) {
-				// Ignore
+			catch (Throwable ignored) {
 			}
 		}
 	}

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) {
-				// ignore
+			catch (InterruptedException ignored) {
 			}
 		}
 

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) {
-				// ignore
+			catch (IOException ignored) {
 			}
 			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) {
-				// ignore
+			catch (ClassNotFoundException ignored) {
 			}
 		}
 	}