Avoid unnecessary generics on emptyMap/Set/List

spring-context/src/main/java/org/springframework/cache/interceptor/CacheAspectSupport.java

@@ -555,7 +555,7 @@ public abstract class CacheAspectSupport extends AbstractCacheInvoker
 
 		public Collection<CacheOperationContext> get(Class<? extends CacheOperation> operationClass) {
 			Collection<CacheOperationContext> result = this.contexts.get(operationClass);
-			return (result != null ? result : Collections.<CacheOperationContext>emptyList());
+			return (result != null ? result : Collections.emptyList());
 		}
 
 		public boolean isSynchronized() {

spring-context/src/main/java/org/springframework/scheduling/config/ScheduledTaskRegistrar.java

@@ -134,7 +134,7 @@ public class ScheduledTaskRegistrar implements InitializingBean, DisposableBean
 	 */
 	public List<TriggerTask> getTriggerTaskList() {
 		return (this.triggerTasks != null? Collections.unmodifiableList(this.triggerTasks) :
-				Collections.<TriggerTask>emptyList());
+				Collections.emptyList());
 	}
 
 	/**
@@ -165,7 +165,7 @@ public class ScheduledTaskRegistrar implements InitializingBean, DisposableBean
 	 */
 	public List<CronTask> getCronTaskList() {
 		return (this.cronTasks != null ? Collections.unmodifiableList(this.cronTasks) :
-				Collections.<CronTask>emptyList());
+				Collections.emptyList());
 	}
 
 	/**
@@ -196,7 +196,7 @@ public class ScheduledTaskRegistrar implements InitializingBean, DisposableBean
 	 */
 	public List<IntervalTask> getFixedRateTaskList() {
 		return (this.fixedRateTasks != null ? Collections.unmodifiableList(this.fixedRateTasks) :
-				Collections.<IntervalTask>emptyList());
+				Collections.emptyList());
 	}
 
 	/**
@@ -227,7 +227,7 @@ public class ScheduledTaskRegistrar implements InitializingBean, DisposableBean
 	 */
 	public List<IntervalTask> getFixedDelayTaskList() {
 		return (this.fixedDelayTasks != null ? Collections.unmodifiableList(this.fixedDelayTasks) :
-				Collections.<IntervalTask>emptyList());
+				Collections.emptyList());
 	}
 
 

spring-core/src/main/java/org/springframework/core/Conventions.java

@@ -50,13 +50,10 @@ public abstract class Conventions {
 	 * when searching for the 'primary' interface of a proxy.
 	 */
 	private static final Set<Class<?>> IGNORED_INTERFACES;
+
 	static {
-		IGNORED_INTERFACES = Collections.unmodifiableSet(
-				new HashSet<>(Arrays.<Class<?>>asList(
-						Serializable.class,
-						Externalizable.class,
-						Cloneable.class,
-						Comparable.class)));
+		IGNORED_INTERFACES = Collections.unmodifiableSet(new HashSet<>(
+				Arrays.asList(Serializable.class, Externalizable.class, Cloneable.class, Comparable.class)));
 	}
 
 

spring-core/src/main/java/org/springframework/core/env/JOptCommandLinePropertySource.java

@@ -101,7 +101,7 @@ public class JOptCommandLinePropertySource extends CommandLinePropertySource<Opt
 			stringArgValues.add(argValue instanceof String ? (String) argValue : argValue.toString());
 		}
 		if (stringArgValues.isEmpty()) {
-			return (this.source.has(name) ? Collections.<String>emptyList() : null);
+			return (this.source.has(name) ? Collections.emptyList() : null);
 		}
 		return Collections.unmodifiableList(stringArgValues);
 	}
@@ -114,7 +114,7 @@ public class JOptCommandLinePropertySource extends CommandLinePropertySource<Opt
 			Assert.isInstanceOf(String.class, argValue, "Argument values must be of type String");
 			stringArgValues.add((String) argValue);
 		}
-		return (stringArgValues.isEmpty() ? Collections.<String>emptyList() :
+		return (stringArgValues.isEmpty() ? Collections.emptyList() :
 				Collections.unmodifiableList(stringArgValues));
 	}
 

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

 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -54,8 +54,8 @@ public class InstanceFilter<T> {
 	public InstanceFilter(Collection<? extends T> includes,
 			Collection<? extends T> excludes, boolean matchIfEmpty) {
 
-		this.includes = includes != null ? includes : Collections.<T>emptyList();
-		this.excludes = excludes != null ? excludes : Collections.<T>emptyList();
+		this.includes = (includes != null ? includes : Collections.emptyList());
+		this.excludes = (excludes != null ? excludes : Collections.emptyList());
 		this.matchIfEmpty = matchIfEmpty;
 	}
 
@@ -64,7 +64,7 @@ public class InstanceFilter<T> {
 	 * Determine if the specified {code instance} matches this filter.
 	 */
 	public boolean match(T instance) {
-		Assert.notNull(instance, "The instance to match is mandatory");
+		Assert.notNull(instance, "Instance to match must not be null");
 
 		boolean includesSet = !this.includes.isEmpty();
 		boolean excludesSet = !this.excludes.isEmpty();
@@ -74,11 +74,9 @@ public class InstanceFilter<T> {
 
 		boolean matchIncludes = match(instance, this.includes);
 		boolean matchExcludes = match(instance, this.excludes);
-
 		if (!includesSet) {
 			return !matchExcludes;
 		}
-
 		if (!excludesSet) {
 			return matchIncludes;
 		}

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

@@ -120,7 +120,7 @@ public class MimeType implements Comparable<MimeType>, Serializable {
 	 * @throws IllegalArgumentException if any of the parameters contains illegal characters
 	 */
 	public MimeType(String type, String subtype) {
-		this(type, subtype, Collections.<String, String>emptyMap());
+		this(type, subtype, Collections.emptyMap());
 	}
 
 	/**

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

@@ -87,7 +87,7 @@ public class SimpleNamespaceContext implements NamespaceContext {
 		}
 		else {
 			Set<String> prefixes = this.namespaceUriToPrefixes.get(namespaceUri);
-			return (prefixes != null ?  Collections.unmodifiableSet(prefixes) : Collections.<String>emptySet());
+			return (prefixes != null ?  Collections.unmodifiableSet(prefixes) : Collections.emptySet());
 		}
 	}
 

spring-expression/src/main/java/org/springframework/expression/spel/ExpressionState.java

@@ -183,7 +183,7 @@ public class ExpressionState {
 
 	public void enterScope() {
 		ensureVariableScopesInitialized();
-		this.variableScopes.push(new VariableScope(Collections.<String,Object>emptyMap()));
+		this.variableScopes.push(new VariableScope(Collections.emptyMap()));
 		this.scopeRootObjects.push(getActiveContextObject());
 	}
 

spring-messaging/src/main/java/org/springframework/messaging/handler/DestinationPatternsMessageCondition.java

@@ -73,7 +73,7 @@ public class DestinationPatternsMessageCondition extends AbstractMessageConditio
 
 
 	private static List<String> asList(String... patterns) {
-		return (patterns != null ? Arrays.asList(patterns) : Collections.<String>emptyList());
+		return (patterns != null ? Arrays.asList(patterns) : Collections.emptyList());
 	}
 
 	private static Set<String> prependLeadingSlash(Collection<String> patterns, PathMatcher pathMatcher) {

spring-messaging/src/main/java/org/springframework/messaging/simp/broker/AbstractBrokerMessageHandler.java

 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -84,7 +84,7 @@ public abstract class AbstractBrokerMessageHandler
 	public AbstractBrokerMessageHandler(SubscribableChannel inboundChannel, MessageChannel outboundChannel,
 			SubscribableChannel brokerChannel) {
 
-		this(inboundChannel, outboundChannel, brokerChannel, Collections.<String>emptyList());
+		this(inboundChannel, outboundChannel, brokerChannel, Collections.emptyList());
 	}
 
 	/**
@@ -105,7 +105,7 @@ public abstract class AbstractBrokerMessageHandler
 		this.clientOutboundChannel = outboundChannel;
 		this.brokerChannel = brokerChannel;
 
-		destinationPrefixes = (destinationPrefixes != null) ? destinationPrefixes : Collections.<String>emptyList();
+		destinationPrefixes = (destinationPrefixes != null) ? destinationPrefixes : Collections.emptyList();
 		this.destinationPrefixes = Collections.unmodifiableCollection(destinationPrefixes);
 	}
 

spring-messaging/src/main/java/org/springframework/messaging/simp/config/AbstractBrokerRegistration.java

 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -50,8 +50,8 @@ public abstract class AbstractBrokerRegistration {
 		this.clientInboundChannel = clientInboundChannel;
 		this.clientOutboundChannel = clientOutboundChannel;
 
-		this.destinationPrefixes = (destinationPrefixes != null)
-				? Arrays.<String>asList(destinationPrefixes) : Collections.<String>emptyList();
+		this.destinationPrefixes = (destinationPrefixes != null ?
+				Arrays.asList(destinationPrefixes) : Collections.emptyList());
 	}
 
 
@@ -67,6 +67,7 @@ public abstract class AbstractBrokerRegistration {
 		return this.destinationPrefixes;
 	}
 
+
 	protected abstract AbstractBrokerMessageHandler getMessageHandler(SubscribableChannel brokerChannel);
 
 }

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

@@ -182,7 +182,7 @@ public class StompHeaderAccessor extends SimpMessageHeaderAccessor {
 	Map<String, List<String>> getNativeHeaders() {
 		@SuppressWarnings("unchecked")
 		Map<String, List<String>> map = (Map<String, List<String>>) getHeader(NATIVE_HEADERS);
-		return (map != null ? map : Collections.<String, List<String>>emptyMap());
+		return (map != null ? map : Collections.emptyMap());
 	}
 
 	public StompCommand updateStompCommandAsClientMessage() {
@@ -242,7 +242,7 @@ public class StompHeaderAccessor extends SimpMessageHeaderAccessor {
 
 	public Set<String> getAcceptVersion() {
 		String rawValue = getFirstNativeHeader(STOMP_ACCEPT_VERSION_HEADER);
-		return (rawValue != null ? StringUtils.commaDelimitedListToSet(rawValue) : Collections.<String>emptySet());
+		return (rawValue != null ? StringUtils.commaDelimitedListToSet(rawValue) : Collections.emptySet());
 	}
 
 	public void setHost(String host) {

spring-messaging/src/main/java/org/springframework/messaging/simp/user/DefaultUserDestinationResolver.java

@@ -188,7 +188,7 @@ public class DefaultUserDestinationResolver implements UserDestinationResolver {
 					}
 				}
 				else {
-					sessionIds = Collections.<String>emptySet();
+					sessionIds = Collections.emptySet();
 				}
 			}
 			if (!this.keepLeadingSlash) {

spring-messaging/src/main/java/org/springframework/messaging/support/NativeMessageHeaderAccessor.java

@@ -94,7 +94,7 @@ public class NativeMessageHeaderAccessor extends MessageHeaderAccessor {
 	 */
 	public Map<String, List<String>> toNativeHeaderMap() {
 		Map<String, List<String>> map = getNativeHeaders();
-		return (map != null ? new LinkedMultiValueMap<>(map) : Collections.<String, List<String>>emptyMap());
+		return (map != null ? new LinkedMultiValueMap<>(map) : Collections.emptyMap());
 	}
 
 	@Override

spring-messaging/src/main/java/org/springframework/messaging/tcp/reactor/Reactor2TcpClient.java

@@ -299,8 +299,7 @@ public class Reactor2TcpClient<P> implements TcpOperations<P> {
 
 		@Override
 		public ReactorConfiguration read() {
-			return new ReactorConfiguration(
-					Collections.<DispatcherConfiguration>emptyList(), "sync", new Properties());
+			return new ReactorConfiguration(Collections.emptyList(), "sync", new Properties());
 		}
 	}
 

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

@@ -425,13 +425,13 @@ public class MockServletContext implements ServletContext {
 	@Override
 	@Deprecated
 	public Enumeration<Servlet> getServlets() {
-		return Collections.enumeration(Collections.<Servlet>emptySet());
+		return Collections.enumeration(Collections.emptySet());
 	}
 
 	@Override
 	@Deprecated
 	public Enumeration<String> getServletNames() {
-		return Collections.enumeration(Collections.<String>emptySet());
+		return Collections.enumeration(Collections.emptySet());
 	}
 
 	@Override

spring-test/src/main/java/org/springframework/test/context/support/TestPropertySourceUtils.java

@@ -132,7 +132,7 @@ public abstract class TestPropertySourceUtils {
 			if (logger.isTraceEnabled()) {
 				logger.trace(String.format("Processing inlined properties for TestPropertySource attributes %s", attrs));
 			}
-			properties.addAll(0, Arrays.<String>asList(attrs.getProperties()));
+			properties.addAll(0, Arrays.asList(attrs.getProperties()));
 			if (!attrs.isInheritProperties()) {
 				break;
 			}

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

@@ -269,7 +269,7 @@ public class MediaType extends MimeType implements Serializable {
 	 * @throws IllegalArgumentException if any of the parameters contain illegal characters
 	 */
 	public MediaType(String type, String subtype) {
-		super(type, subtype, Collections.<String, String>emptyMap());
+		super(type, subtype, Collections.emptyMap());
 	}
 
 	/**
@@ -463,7 +463,7 @@ public class MediaType extends MimeType implements Serializable {
 	 */
 	public static List<MediaType> parseMediaTypes(List<String> mediaTypes) {
 		if (CollectionUtils.isEmpty(mediaTypes)) {
-			return Collections.<MediaType>emptyList();
+			return Collections.emptyList();
 		}
 		else if (mediaTypes.size() == 1) {
 			return parseMediaTypes(mediaTypes.get(0));

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

@@ -47,7 +47,7 @@ public class InterceptingAsyncClientHttpRequestFactory implements AsyncClientHtt
 			List<AsyncClientHttpRequestInterceptor> interceptors) {
 
 		this.delegate = delegate;
-		this.interceptors = (interceptors != null ? interceptors : Collections.<AsyncClientHttpRequestInterceptor>emptyList());
+		this.interceptors = (interceptors != null ? interceptors : Collections.emptyList());
 	}
 
 

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

 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,7 +42,7 @@ public class InterceptingClientHttpRequestFactory extends AbstractClientHttpRequ
 			List<ClientHttpRequestInterceptor> interceptors) {
 
 		super(requestFactory);
-		this.interceptors = (interceptors != null ? interceptors : Collections.<ClientHttpRequestInterceptor>emptyList());
+		this.interceptors = (interceptors != null ? interceptors : Collections.emptyList());
 	}
 
 	@Override

spring-web/src/main/java/org/springframework/web/accept/HeaderContentNegotiationStrategy.java

@@ -45,7 +45,7 @@ public class HeaderContentNegotiationStrategy implements ContentNegotiationStrat
 
 		String[] headerValueArray = request.getHeaderValues(HttpHeaders.ACCEPT);
 		if (headerValueArray == null) {
-			return Collections.<MediaType>emptyList();
+			return Collections.emptyList();
 		}
 
 		List<String> headerValues = Arrays.asList(headerValueArray);

spring-web/src/main/java/org/springframework/web/accept/MappingMediaTypeFileExtensionResolver.java

@@ -90,7 +90,7 @@ public class MappingMediaTypeFileExtensionResolver implements MediaTypeFileExten
 	@Override
 	public List<String> resolveFileExtensions(MediaType mediaType) {
 		List<String> fileExtensions = this.fileExtensions.get(mediaType);
-		return (fileExtensions != null) ? fileExtensions : Collections.<String>emptyList();
+		return (fileExtensions != null) ? fileExtensions : Collections.emptyList();
 	}
 
 	@Override

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

@@ -213,7 +213,7 @@ public class ForwardedHeaderFilter extends OncePerRequestFilter {
 		@Override
 		public Enumeration<String> getHeaders(String name) {
 			List<String> value = this.headers.get(name);
-			return (Collections.enumeration(value != null ? value : Collections.<String>emptySet()));
+			return (Collections.enumeration(value != null ? value : Collections.emptySet()));
 		}
 
 		@Override

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMethodMapping.java

@@ -590,7 +590,7 @@ public abstract class AbstractHandlerMethodMapping<T> extends AbstractHandlerMap
 		private void addMappingName(String name, HandlerMethod handlerMethod) {
 			List<HandlerMethod> oldList = this.nameLookup.get(name);
 			if (oldList == null) {
-				oldList = Collections.<HandlerMethod>emptyList();
+				oldList = Collections.emptyList();
 			}
 
 			for (HandlerMethod current : oldList) {
@@ -685,7 +685,7 @@ public abstract class AbstractHandlerMethodMapping<T> extends AbstractHandlerMap
 			Assert.notNull(handlerMethod);
 			this.mapping = mapping;
 			this.handlerMethod = handlerMethod;
-			this.directUrls = (directUrls != null ? directUrls : Collections.<String>emptyList());
+			this.directUrls = (directUrls != null ? directUrls : Collections.emptyList());
 			this.mappingName = mappingName;
 		}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/SimpleServletPostProcessor.java

@@ -163,7 +163,7 @@ public class SimpleServletPostProcessor implements
 
 		@Override
 		public Enumeration<String> getInitParameterNames() {
-			return Collections.enumeration(Collections.<String>emptySet());
+			return Collections.enumeration(Collections.emptySet());
 		}
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/PatternsRequestCondition.java

@@ -119,7 +119,7 @@ public final class PatternsRequestCondition extends AbstractRequestCondition<Pat
 
 
 	private static List<String> asList(String... patterns) {
-		return (patterns != null ? Arrays.asList(patterns) : Collections.<String>emptyList());
+		return (patterns != null ? Arrays.asList(patterns) : Collections.emptyList());
 	}
 
 	private static Set<String> prependLeadingSlash(Collection<String> patterns) {

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/RequestMethodsRequestCondition.java

@@ -62,7 +62,7 @@ public final class RequestMethodsRequestCondition extends AbstractRequestConditi
 
 
 	private static List<RequestMethod> asList(RequestMethod... requestMethods) {
-		return (requestMethods != null ? Arrays.asList(requestMethods) : Collections.<RequestMethod>emptyList());
+		return (requestMethods != null ? Arrays.asList(requestMethods) : Collections.emptyList());
 	}
 
 

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

 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -106,7 +106,7 @@ public class ServletModelAttributeMethodProcessor extends ModelAttributeMethodPr
 	protected final Map<String, String> getUriTemplateVariables(NativeWebRequest request) {
 		Map<String, String> variables = (Map<String, String>) request.getAttribute(
 				HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, RequestAttributes.SCOPE_REQUEST);
-		return (variables != null ? variables : Collections.<String, String>emptyMap());
+		return (variables != null ? variables : Collections.emptyMap());
 	}
 
 	/**

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

@@ -235,7 +235,7 @@ public class SseEmitter extends ResponseBodyEmitter {
 		@Override
 		public Set<DataWithMediaType> build() {
 			if ((this.sb == null || this.sb.length() == 0) && this.dataToSend.isEmpty()) {
-				return Collections.<DataWithMediaType>emptySet();
+				return Collections.emptySet();
 			}
 			append("\n");
 			saveAppendedText();

spring-webmvc/src/main/java/org/springframework/web/servlet/view/freemarker/FreeMarkerView.java

@@ -405,7 +405,7 @@ public class FreeMarkerView extends AbstractTemplateView {
 
 		@Override
 		public Enumeration<String> getInitParameterNames() {
-			return Collections.enumeration(Collections.<String>emptySet());
+			return Collections.enumeration(Collections.emptySet());
 		}
 	}
 

spring-websocket/src/main/java/org/springframework/web/socket/client/AbstractWebSocketClient.java

@@ -43,8 +43,6 @@ import org.springframework.web.util.UriComponentsBuilder;
  */
 public abstract class AbstractWebSocketClient implements WebSocketClient {
 
-	protected final Log logger = LogFactory.getLog(getClass());
-
 	private static final Set<String> specialHeaders = new HashSet<>();
 
 	static {
@@ -60,11 +58,14 @@ public abstract class AbstractWebSocketClient implements WebSocketClient {
 	}
 
 
+	protected final Log logger = LogFactory.getLog(getClass());
+
+
 	@Override
 	public ListenableFuture<WebSocketSession> doHandshake(WebSocketHandler webSocketHandler,
 			String uriTemplate, Object... uriVars) {
 
-		Assert.notNull(uriTemplate, "uriTemplate must not be null");
+		Assert.notNull(uriTemplate, "'uriTemplate' must not be null");
 		URI uri = UriComponentsBuilder.fromUriString(uriTemplate).buildAndExpand(uriVars).encode().toUri();
 		return doHandshake(webSocketHandler, null, uri);
 	}
@@ -73,7 +74,7 @@ public abstract class AbstractWebSocketClient implements WebSocketClient {
 	public final ListenableFuture<WebSocketSession> doHandshake(WebSocketHandler webSocketHandler,
 			WebSocketHttpHeaders headers, URI uri) {
 
-		Assert.notNull(webSocketHandler, "webSocketHandler must not be null");
+		Assert.notNull(webSocketHandler, "WebSocketHandler must not be null");
 		assertUri(uri);
 
 		if (logger.isDebugEnabled()) {
@@ -89,25 +90,26 @@ public abstract class AbstractWebSocketClient implements WebSocketClient {
 			}
 		}
 
-		List<String> subProtocols = ((headers != null) && (headers.getSecWebSocketProtocol() != null)) ?
-				headers.getSecWebSocketProtocol() : Collections.<String>emptyList();
+		List<String> subProtocols = (headers != null && headers.getSecWebSocketProtocol() != null ?
+				headers.getSecWebSocketProtocol() : Collections.emptyList());
 
-		List<WebSocketExtension> extensions = ((headers != null) && (headers.getSecWebSocketExtensions() != null)) ?
-				headers.getSecWebSocketExtensions() : Collections.<WebSocketExtension>emptyList();
+		List<WebSocketExtension> extensions = (headers != null && headers.getSecWebSocketExtensions() != null ?
+				headers.getSecWebSocketExtensions() : Collections.emptyList());
 
 		return doHandshakeInternal(webSocketHandler, headersToUse, uri, subProtocols, extensions,
-				Collections.<String, Object>emptyMap());
+				Collections.emptyMap());
 	}
 
 	protected void assertUri(URI uri) {
-		Assert.notNull(uri, "uri must not be null");
+		Assert.notNull(uri, "URI must not be null");
 		String scheme = uri.getScheme();
-		Assert.isTrue(scheme != null && ("ws".equals(scheme) || "wss".equals(scheme)), "Invalid scheme: " + scheme);
+		if (!"ws".equals(scheme) && !"wss".equals(scheme)) {
+			throw new IllegalArgumentException("Invalid scheme: " + scheme);
+		}
 	}
 
 	/**
 	 * Perform the actual handshake to establish a connection to the server.
-	 *
 	 * @param webSocketHandler the client-side handler for WebSocket messages
 	 * @param headers HTTP headers to use for the handshake, with unwanted (forbidden)
 	 * headers filtered out, never {@code null}
@@ -116,7 +118,6 @@ public abstract class AbstractWebSocketClient implements WebSocketClient {
 	 * @param extensions requested WebSocket extensions, or an empty list
 	 * @param attributes attributes to associate with the WebSocketSession, i.e. via
 	 * {@link WebSocketSession#getAttributes()}; currently always an empty map.
-	 *
 	 * @return the established WebSocket session wrapped in a ListenableFuture.
 	 */
 	protected abstract ListenableFuture<WebSocketSession> doHandshakeInternal(WebSocketHandler webSocketHandler,

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

@@ -468,7 +468,7 @@ public class WebSocketStompClient extends StompClientSupport implements SmartLif
 		}
 
 		public List<Message<byte[]>> decode(WebSocketMessage<?> webSocketMessage) {
-			List<Message<byte[]>> result = Collections.<Message<byte[]>>emptyList();
+			List<Message<byte[]>> result = Collections.emptyList();
 			ByteBuffer byteBuffer;
 			if (webSocketMessage instanceof TextMessage) {
 				byteBuffer = ByteBuffer.wrap(((TextMessage) webSocketMessage).asBytes());

spring-websocket/src/main/java/org/springframework/web/socket/server/standard/UndertowRequestUpgradeStrategy.java

@@ -66,7 +66,7 @@ public class UndertowRequestUpgradeStrategy extends AbstractStandardUpgradeStrat
 
 		StringBuffer requestUrl = servletRequest.getRequestURL();
 		String path = servletRequest.getRequestURI();  // shouldn't matter
-		Map<String, String> pathParams = Collections.<String, String>emptyMap();
+		Map<String, String> pathParams = Collections.emptyMap();
 
 		ServerEndpointRegistration endpointConfig = new ServerEndpointRegistration(path, endpoint);
 		endpointConfig.setSubprotocols(Collections.singletonList(selectedProtocol));

spring-websocket/src/main/java/org/springframework/web/socket/server/support/AbstractHandshakeHandler.java

@@ -367,7 +367,7 @@ public abstract class AbstractHandshakeHandler implements HandshakeHandler, Life
 		if (handlerToCheck instanceof SubProtocolCapable) {
 			subProtocols = ((SubProtocolCapable) handlerToCheck).getSubProtocols();
 		}
-		return (subProtocols != null ? subProtocols : Collections.<String>emptyList());
+		return (subProtocols != null ? subProtocols : Collections.emptyList());
 	}
 
 	/**

spring-websocket/src/main/java/org/springframework/web/socket/server/support/HandshakeInterceptorChain.java

 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -46,7 +46,7 @@ public class HandshakeInterceptorChain {
 
 
 	public HandshakeInterceptorChain(List<HandshakeInterceptor> interceptors, WebSocketHandler wsHandler) {
-		this.interceptors = (interceptors != null ? interceptors : Collections.<HandshakeInterceptor>emptyList());
+		this.interceptors = (interceptors != null ? interceptors : Collections.emptyList());
 		this.wsHandler = wsHandler;
 	}