Apply SingleSpaceSeparator Checkstyle module

This commit also fixes its violations.

Closes gh-31469

spring-core/src/main/java/org/springframework/aot/hint/support/KotlinDetectorRuntimeHints.java

@@ -26,7 +26,7 @@ import org.springframework.aot.hint.TypeReference;
  * @author Brian Clozel
  * @since 6.1
  */
-class KotlinDetectorRuntimeHints  implements RuntimeHintsRegistrar {
+class KotlinDetectorRuntimeHints implements RuntimeHintsRegistrar {
 
 	@Override
 	public void registerHints(RuntimeHints hints, ClassLoader classLoader) {

spring-core/src/main/java/org/springframework/core/annotation/AnnotationAwareOrderComparator.java

@@ -92,7 +92,7 @@ public class AnnotationAwareOrderComparator extends OrderComparator {
 			return OrderUtils.getPriority(clazz);
 		}
 		Integer priority = OrderUtils.getPriority(obj.getClass());
-		if (priority == null  && obj instanceof DecoratingProxy decoratingProxy) {
+		if (priority == null && obj instanceof DecoratingProxy decoratingProxy) {
 			return getPriority(decoratingProxy.getDecoratedClass());
 		}
 		return priority;

spring-core/src/main/java/org/springframework/core/io/UrlResource.java

@@ -129,7 +129,7 @@ public class UrlResource extends AbstractFileResolvingResource {
 	 * @throws MalformedURLException if the given URL specification is not valid
 	 * @see java.net.URI#URI(String, String, String)
 	 */
-	public UrlResource(String protocol, String location) throws MalformedURLException  {
+	public UrlResource(String protocol, String location) throws MalformedURLException {
 		this(protocol, location, null);
 	}
 
@@ -145,7 +145,7 @@ public class UrlResource extends AbstractFileResolvingResource {
 	 * @throws MalformedURLException if the given URL specification is not valid
 	 * @see java.net.URI#URI(String, String, String)
 	 */
-	public UrlResource(String protocol, String location, @Nullable String fragment) throws MalformedURLException  {
+	public UrlResource(String protocol, String location, @Nullable String fragment) throws MalformedURLException {
 		try {
 			this.uri = new URI(protocol, location, fragment);
 			this.url = this.uri.toURL();

spring-core/src/main/java/org/springframework/core/io/buffer/DataBufferUtils.java

@@ -1074,7 +1074,7 @@ public abstract class DataBufferUtils {
 			DataBuffer.ByteBufferIterator iterator = dataBuffer.writableByteBuffers();
 			Assert.state(iterator.hasNext(), "No ByteBuffer available");
 			ByteBuffer byteBuffer = iterator.next();
-			Attachment attachment = new Attachment(dataBuffer,  iterator);
+			Attachment attachment = new Attachment(dataBuffer, iterator);
 			this.channel.read(byteBuffer, this.position.get(), attachment, this);
 		}
 

spring-core/src/main/java/org/springframework/core/serializer/support/SerializingConverter.java

@@ -56,7 +56,7 @@ public class SerializingConverter implements Converter<Object, byte[]> {
 	 */
 	@Override
 	public byte[] convert(Object source) {
-		try  {
+		try {
 			return this.serializer.serializeToByteArray(source);
 		}
 		catch (Throwable ex) {

spring-core/src/main/java/org/springframework/util/xml/SimpleNamespaceContext.java

@@ -90,7 +90,7 @@ public class SimpleNamespaceContext implements NamespaceContext {
 		}
 		else {
 			Set<String> prefixes = this.namespaceUriToPrefixes.get(namespaceUri);
-			return (prefixes != null ?  Collections.unmodifiableSet(prefixes) : Collections.emptySet());
+			return (prefixes != null ? Collections.unmodifiableSet(prefixes) : Collections.emptySet());
 		}
 	}
 

spring-core/src/test/java/org/springframework/core/BridgeMethodResolverTests.java

@@ -252,7 +252,7 @@ class BridgeMethodResolverTests {
 		Method bridgedMethod = MegaMessageProducerImpl.class.getDeclaredMethod("receive", MegaMessageEvent.class);
 		assertThat(bridgedMethod.isBridge()).isFalse();
 
-		Method bridgeMethod  = MegaMessageProducerImpl.class.getDeclaredMethod("receive", MegaEvent.class);
+		Method bridgeMethod = MegaMessageProducerImpl.class.getDeclaredMethod("receive", MegaEvent.class);
 		assertThat(bridgeMethod.isBridge()).isTrue();
 
 		assertThat(BridgeMethodResolver.findBridgedMethod(bridgeMethod)).isEqualTo(bridgedMethod);

spring-core/src/test/java/org/springframework/core/codec/CharBufferDecoderTests.java

@@ -128,7 +128,7 @@ class CharBufferDecoderTests extends AbstractDecoderTests<CharBufferDecoder> {
 	}
 
 	@Test
-	void decodeNewlinesAcrossBuffers()  {
+	void decodeNewlinesAcrossBuffers() {
 		Flux<DataBuffer> input = Flux.just(
 				stringBuffer("\r"),
 				stringBuffer("\n"),

spring-core/src/test/java/org/springframework/core/codec/StringDecoderTests.java

@@ -139,7 +139,7 @@ class StringDecoderTests extends AbstractDecoderTests<StringDecoder> {
 	}
 
 	@Test
-	void decodeNewlinesAcrossBuffers()  {
+	void decodeNewlinesAcrossBuffers() {
 		Flux<DataBuffer> input = Flux.just(
 				stringBuffer("\r"),
 				stringBuffer("\n"),

spring-core/src/test/java/org/springframework/core/convert/support/GenericConversionServiceTests.java

@@ -633,7 +633,7 @@ class GenericConversionServiceTests {
 	}
 
 
-	private static class MyStringToIntegerArrayConverter implements Converter<String, Integer[]>	{
+	private static class MyStringToIntegerArrayConverter implements Converter<String, Integer[]> {
 
 		@Override
 		public Integer[] convert(String source) {

spring-core/src/test/java/org/springframework/core/io/support/PathMatchingResourcePatternResolverTests.java

@@ -200,7 +200,7 @@ class PathMatchingResourcePatternResolverTests {
 			}
 
 			@Test
-			void usingFileProtocolWithoutWildcardInPatternAndEndingInSlashStarStar()  {
+			void usingFileProtocolWithoutWildcardInPatternAndEndingInSlashStarStar() {
 				Path testResourcesDir = Paths.get("src/test/resources").toAbsolutePath();
 				String pattern = String.format("file:%s/scanned-resources/**", testResourcesDir);
 				String pathPrefix = ".+?resources/";