Apply SingleSpaceSeparator Checkstyle module

This commit also fixes its violations.

Closes gh-31469

spring-websocket/src/test/java/org/springframework/web/socket/config/MessageBrokerBeanDefinitionParserTests.java

@@ -433,10 +433,10 @@ public class MessageBrokerBeanDefinitionParserTests {
 
 
 	private void testChannel(
-			String channelName, List<Class<? extends  MessageHandler>> subscriberTypes, int interceptorCount) {
+			String channelName, List<Class<? extends MessageHandler>> subscriberTypes, int interceptorCount) {
 
 		AbstractSubscribableChannel channel = this.appContext.getBean(channelName, AbstractSubscribableChannel.class);
-		for (Class<? extends  MessageHandler> subscriberType : subscriberTypes) {
+		for (Class<? extends MessageHandler> subscriberType : subscriberTypes) {
 			MessageHandler subscriber = this.appContext.getBean(subscriberType);
 			assertThat(subscriber).as("No subscription for " + subscriberType).isNotNull();
 			assertThat(channel.hasSubscription(subscriber)).isTrue();

spring-websocket/src/test/java/org/springframework/web/socket/handler/BeanCreatingHandlerProviderTests.java

@@ -92,6 +92,6 @@ public class BeanCreatingHandlerProviderTests {
 		}
 	}
 
-	private static class EchoService {	}
+	private static class EchoService { }
 
 }

spring-websocket/src/test/java/org/springframework/web/socket/server/standard/ServerEndpointRegistrationTests.java

@@ -87,6 +87,6 @@ public class ServerEndpointRegistrationTests {
 		}
 	}
 
-	private static class EchoService {	}
+	private static class EchoService { }
 
 }

spring-websocket/src/test/java/org/springframework/web/socket/server/standard/SpringConfiguratorTests.java

@@ -135,6 +135,6 @@ public class SpringConfiguratorTests {
 		}
 	}
 
-	private static class EchoService {	}
+	private static class EchoService { }
 
 }