@Nullable all the way: null-safety at field level

This commits extends nullability declarations to the field level, formalizing the interaction between methods and their underlying fields and therefore avoiding any nullability mismatch.

Issue: SPR-15720

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

@@ -40,28 +40,38 @@ import static java.time.format.DateTimeFormatter.*;
  */
 public class ContentDisposition {
 
+	@Nullable
 	private final String type;
 
+	@Nullable
 	private final String name;
 
+	@Nullable
 	private final String filename;
 
+	@Nullable
 	private final Charset charset;
 
+	@Nullable
 	private final Long size;
 
+	@Nullable
 	private final ZonedDateTime creationDate;
 
+	@Nullable
 	private final ZonedDateTime modificationDate;
 
+	@Nullable
 	private final ZonedDateTime readDate;
 
 
 	/**
 	 * Private constructor. See static factory methods in this class.
 	 */
-	private ContentDisposition(@Nullable String type, @Nullable String name, @Nullable String filename, @Nullable Charset charset, @Nullable Long size,
-			@Nullable ZonedDateTime creationDate, @Nullable ZonedDateTime modificationDate, @Nullable ZonedDateTime readDate) {
+	private ContentDisposition(@Nullable String type, @Nullable String name, @Nullable String filename,
+			@Nullable Charset charset, @Nullable Long size, @Nullable ZonedDateTime creationDate,
+			@Nullable ZonedDateTime modificationDate, @Nullable ZonedDateTime readDate) {
+
 		this.type = type;
 		this.name = name;
 		this.filename = filename;
@@ -435,28 +445,34 @@ public class ContentDisposition {
 		 * Build the content disposition
 		 */
 		ContentDisposition build();
-
 	}
 
+
 	private static class BuilderImpl implements Builder {
 
 		private String type;
 
+		@Nullable
 		private String name;
 
+		@Nullable
 		private String filename;
 
+		@Nullable
 		private Charset charset;
 
+		@Nullable
 		private Long size;
 
+		@Nullable
 		private ZonedDateTime creationDate;
 
+		@Nullable
 		private ZonedDateTime modificationDate;
 
+		@Nullable
 		private ZonedDateTime readDate;
 
-
 		public BuilderImpl(String type) {
 			Assert.hasText(type, "'type' must not be not empty");
 			this.type = type;

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

@@ -64,6 +64,7 @@ public class HttpEntity<T> {
 
 	private final HttpHeaders headers;
 
+	@Nullable
 	private final T body;
 
 
@@ -151,13 +152,9 @@ public class HttpEntity<T> {
 		StringBuilder builder = new StringBuilder("<");
 		if (this.body != null) {
 			builder.append(this.body);
-			if (this.headers != null) {
-				builder.append(',');
-			}
-		}
-		if (this.headers != null) {
-			builder.append(this.headers);
+			builder.append(',');
 		}
+		builder.append(this.headers);
 		builder.append('>');
 		return builder.toString();
 	}

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

@@ -212,6 +212,7 @@ public abstract class HttpRange {
 
 		private final long firstPos;
 
+		@Nullable
 		private final Long lastPos;
 
 		public ByteRange(long firstPos, @Nullable Long lastPos) {

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

@@ -62,10 +62,12 @@ import org.springframework.util.ObjectUtils;
  */
 public class RequestEntity<T> extends HttpEntity<T> {
 
+	@Nullable
 	private final HttpMethod method;
 
 	private final URI url;
 
+	@Nullable
 	private final Type type;
 
 

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

@@ -49,7 +49,7 @@ abstract class AbstractBufferingAsyncClientHttpRequest extends AbstractAsyncClie
 			headers.setContentLength(bytes.length);
 		}
 		ListenableFuture<ClientHttpResponse> result = executeInternal(headers, bytes);
-		this.bufferedOutput = null;
+		this.bufferedOutput = new ByteArrayOutputStream(0);
 		return result;
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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 @@ abstract class AbstractBufferingClientHttpRequest extends AbstractClientHttpRequ
 			headers.setContentLength(bytes.length);
 		}
 		ClientHttpResponse result = executeInternal(headers, bytes);
-		this.bufferedOutput = null;
+		this.bufferedOutput = new ByteArrayOutputStream(0);
 		return result;
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -22,6 +22,7 @@ import java.io.InputStream;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StreamUtils;
 
 /**
@@ -35,6 +36,7 @@ final class BufferingClientHttpResponseWrapper implements ClientHttpResponse {
 
 	private final ClientHttpResponse response;
 
+	@Nullable
 	private byte[] body;
 
 

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

@@ -33,6 +33,7 @@ import org.apache.http.protocol.HttpContext;
 
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.http.HttpMethod;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -50,6 +51,7 @@ import org.springframework.util.Assert;
 public class HttpComponentsAsyncClientHttpRequestFactory extends HttpComponentsClientHttpRequestFactory
 		implements AsyncClientHttpRequestFactory, InitializingBean {
 
+	@Nullable
 	private HttpAsyncClient asyncClient;
 
 
@@ -126,6 +128,7 @@ public class HttpComponentsAsyncClientHttpRequestFactory extends HttpComponentsC
 	 * @since 4.3.10
 	 * @see #getHttpClient()
 	 */
+	@Nullable
 	public HttpAsyncClient getAsyncClient() {
 		return this.asyncClient;
 	}
@@ -158,19 +161,21 @@ public class HttpComponentsAsyncClientHttpRequestFactory extends HttpComponentsC
 		startAsyncClient();
 	}
 
-	private void startAsyncClient() {
-        HttpAsyncClient asyncClient = getAsyncClient();
-		if (asyncClient instanceof CloseableHttpAsyncClient) {
-			CloseableHttpAsyncClient closeableAsyncClient = (CloseableHttpAsyncClient) asyncClient;
+	private HttpAsyncClient startAsyncClient() {
+        HttpAsyncClient client = getAsyncClient();
+		Assert.state(client != null, "No HttpAsyncClient set");
+		if (client instanceof CloseableHttpAsyncClient) {
+			CloseableHttpAsyncClient closeableAsyncClient = (CloseableHttpAsyncClient) client;
 			if (!closeableAsyncClient.isRunning()) {
 				closeableAsyncClient.start();
 			}
 		}
+		return client;
 	}
 
 	@Override
 	public AsyncClientHttpRequest createAsyncRequest(URI uri, HttpMethod httpMethod) throws IOException {
-		startAsyncClient();
+		HttpAsyncClient client = startAsyncClient();
 
 		HttpUriRequest httpRequest = createHttpUriRequest(httpMethod, uri);
 		postProcessHttpRequest(httpRequest);
@@ -187,14 +192,14 @@ public class HttpComponentsAsyncClientHttpRequestFactory extends HttpComponentsC
 				config = ((Configurable) httpRequest).getConfig();
 			}
 			if (config == null) {
-				config = createRequestConfig(getAsyncClient());
+				config = createRequestConfig(client);
 			}
 			if (config != null) {
 				context.setAttribute(HttpClientContext.REQUEST_CONFIG, config);
 			}
 		}
 
-		return new HttpComponentsAsyncClientHttpRequest(getAsyncClient(), httpRequest, context);
+		return new HttpComponentsAsyncClientHttpRequest(client, httpRequest, context);
 	}
 
 	@Override

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

@@ -24,6 +24,7 @@ import org.apache.http.HttpEntity;
 import org.apache.http.HttpResponse;
 
 import org.springframework.http.HttpHeaders;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StreamUtils;
 
 /**
@@ -43,6 +44,7 @@ final class HttpComponentsAsyncClientHttpResponse extends AbstractClientHttpResp
 
 	private final HttpResponse httpResponse;
 
+	@Nullable
 	private HttpHeaders headers;
 
 

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

@@ -59,8 +59,10 @@ import org.springframework.util.Assert;
  */
 public class HttpComponentsClientHttpRequestFactory implements ClientHttpRequestFactory, DisposableBean {
 
+	@Nullable
 	private HttpClient httpClient;
 
+	@Nullable
 	private RequestConfig requestConfig;
 
 	private boolean bufferRequestBody = true;
@@ -97,6 +99,7 @@ public class HttpComponentsClientHttpRequestFactory implements ClientHttpRequest
 	 * Return the {@code HttpClient} used for
 	 * {@linkplain #createRequest(URI, HttpMethod) synchronous execution}.
 	 */
+	@Nullable
 	public HttpClient getHttpClient() {
 		return this.httpClient;
 	}
@@ -152,6 +155,9 @@ public class HttpComponentsClientHttpRequestFactory implements ClientHttpRequest
 
 	@Override
 	public ClientHttpRequest createRequest(URI uri, HttpMethod httpMethod) throws IOException {
+		HttpClient client = getHttpClient();
+		Assert.state(client != null, "No HttpClient set");
+
 		HttpUriRequest httpRequest = createHttpUriRequest(httpMethod, uri);
 		postProcessHttpRequest(httpRequest);
 		HttpContext context = createHttpContext(httpMethod, uri);
@@ -167,7 +173,7 @@ public class HttpComponentsClientHttpRequestFactory implements ClientHttpRequest
 				config = ((Configurable) httpRequest).getConfig();
 			}
 			if (config == null) {
-				config = createRequestConfig(getHttpClient());
+				config = createRequestConfig(client);
 			}
 			if (config != null) {
 				context.setAttribute(HttpClientContext.REQUEST_CONFIG, config);
@@ -175,10 +181,10 @@ public class HttpComponentsClientHttpRequestFactory implements ClientHttpRequest
 		}
 
 		if (this.bufferRequestBody) {
-			return new HttpComponentsClientHttpRequest(getHttpClient(), httpRequest, context);
+			return new HttpComponentsClientHttpRequest(client, httpRequest, context);
 		}
 		else {
-			return new HttpComponentsStreamingClientHttpRequest(getHttpClient(), httpRequest, context);
+			return new HttpComponentsStreamingClientHttpRequest(client, httpRequest, context);
 		}
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -26,6 +26,7 @@ import org.apache.http.HttpResponse;
 import org.apache.http.util.EntityUtils;
 
 import org.springframework.http.HttpHeaders;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StreamUtils;
 
 /**
@@ -43,6 +44,7 @@ final class HttpComponentsClientHttpResponse extends AbstractClientHttpResponse
 
 	private final HttpResponse httpResponse;
 
+	@Nullable
 	private HttpHeaders headers;
 
 

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

@@ -54,6 +54,7 @@ final class HttpComponentsStreamingClientHttpRequest extends AbstractClientHttpR
 
 	private final HttpContext httpContext;
 
+	@Nullable
 	private Body body;
 
 
@@ -89,9 +90,9 @@ final class HttpComponentsStreamingClientHttpRequest extends AbstractClientHttpR
 	protected ClientHttpResponse executeInternal(HttpHeaders headers) throws IOException {
 		HttpComponentsClientHttpRequest.addHeaders(this.httpRequest, headers);
 
-		if (this.httpRequest instanceof HttpEntityEnclosingRequest && body != null) {
+		if (this.httpRequest instanceof HttpEntityEnclosingRequest && this.body != null) {
 			HttpEntityEnclosingRequest entityEnclosingRequest = (HttpEntityEnclosingRequest) this.httpRequest;
-			HttpEntity requestEntity = new StreamingHttpEntity(getHeaders(), body);
+			HttpEntity requestEntity = new StreamingHttpEntity(getHeaders(), this.body);
 			entityEnclosingRequest.setEntity(requestEntity);
 		}
 

spring-web/src/main/java/org/springframework/http/client/Netty4ClientHttpRequestFactory.java

@@ -39,6 +39,7 @@ import io.netty.handler.timeout.ReadTimeoutHandler;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.http.HttpMethod;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -75,12 +76,14 @@ public class Netty4ClientHttpRequestFactory implements ClientHttpRequestFactory,
 
 	private int maxResponseSize = DEFAULT_MAX_RESPONSE_SIZE;
 
+	@Nullable
 	private SslContext sslContext;
 
 	private int connectTimeout = -1;
 
 	private int readTimeout = -1;
 
+	@Nullable
 	private volatile Bootstrap bootstrap;
 
 
@@ -183,10 +186,12 @@ public class Netty4ClientHttpRequestFactory implements ClientHttpRequestFactory,
 			return buildBootstrap(uri, true);
 		}
 		else {
-			if (this.bootstrap == null) {
-				this.bootstrap = buildBootstrap(uri, false);
+			Bootstrap bootstrap = this.bootstrap;
+			if (bootstrap == null) {
+				bootstrap = buildBootstrap(uri, false);
+				this.bootstrap = bootstrap;
 			}
-			return this.bootstrap;
+			return bootstrap;
 		}
 	}
 

spring-web/src/main/java/org/springframework/http/client/Netty4ClientHttpResponse.java

@@ -25,6 +25,7 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.http.FullHttpResponse;
 
 import org.springframework.http.HttpHeaders;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -43,6 +44,7 @@ class Netty4ClientHttpResponse extends AbstractClientHttpResponse {
 
 	private final ByteBufInputStream body;
 
+	@Nullable
 	private volatile HttpHeaders headers;
 
 
@@ -70,14 +72,15 @@ class Netty4ClientHttpResponse extends AbstractClientHttpResponse {
 
 	@Override
 	public HttpHeaders getHeaders() {
-		if (this.headers == null) {
-			HttpHeaders headers = new HttpHeaders();
+		HttpHeaders headers = this.headers;
+		if (headers == null) {
+			headers = new HttpHeaders();
 			for (Map.Entry<String, String> entry : this.nettyResponse.headers()) {
 				headers.add(entry.getKey(), entry.getValue());
 			}
 			this.headers = headers;
 		}
-		return this.headers;
+		return headers;
 	}
 
 	@Override

spring-web/src/main/java/org/springframework/http/client/OkHttp3ClientHttpResponse.java

@@ -23,6 +23,7 @@ import okhttp3.Response;
 import okhttp3.ResponseBody;
 
 import org.springframework.http.HttpHeaders;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StreamUtils;
 
@@ -38,7 +39,8 @@ class OkHttp3ClientHttpResponse extends AbstractClientHttpResponse {
 
 	private final Response response;
 
-	private HttpHeaders headers;
+	@Nullable
+	private volatile HttpHeaders headers;
 
 
 	public OkHttp3ClientHttpResponse(Response response) {
@@ -65,8 +67,9 @@ class OkHttp3ClientHttpResponse extends AbstractClientHttpResponse {
 
 	@Override
 	public HttpHeaders getHeaders() {
-		if (this.headers == null) {
-			HttpHeaders headers = new HttpHeaders();
+		HttpHeaders headers = this.headers;
+		if (headers == null) {
+			headers = new HttpHeaders();
 			for (String headerName : this.response.headers().names()) {
 				for (String headerValue : this.response.headers(headerName)) {
 					headers.add(headerName, headerValue);
@@ -74,7 +77,7 @@ class OkHttp3ClientHttpResponse extends AbstractClientHttpResponse {
 			}
 			this.headers = headers;
 		}
-		return this.headers;
+		return headers;
 	}
 
 	@Override

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

@@ -43,6 +43,7 @@ public class SimpleClientHttpRequestFactory implements ClientHttpRequestFactory,
 	private static final int DEFAULT_CHUNK_SIZE = 4096;
 
 
+	@Nullable
 	private Proxy proxy;
 
 	private boolean bufferRequestBody = true;
@@ -55,6 +56,7 @@ public class SimpleClientHttpRequestFactory implements ClientHttpRequestFactory,
 
 	private boolean outputStreaming = true;
 
+	@Nullable
 	private AsyncListenableTaskExecutor taskExecutor;
 
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -21,6 +21,7 @@ import java.io.InputStream;
 import java.net.HttpURLConnection;
 
 import org.springframework.http.HttpHeaders;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StreamUtils;
 import org.springframework.util.StringUtils;
 
@@ -37,8 +38,10 @@ final class SimpleClientHttpResponse extends AbstractClientHttpResponse {
 
 	private final HttpURLConnection connection;
 
+	@Nullable
 	private HttpHeaders headers;
 
+	@Nullable
 	private InputStream responseStream;
 
 

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

@@ -25,6 +25,7 @@ import java.util.concurrent.Callable;
 
 import org.springframework.core.task.AsyncListenableTaskExecutor;
 import org.springframework.http.HttpHeaders;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StreamUtils;
 import org.springframework.util.concurrent.ListenableFuture;
 
@@ -45,6 +46,7 @@ final class SimpleStreamingAsyncClientHttpRequest extends AbstractAsyncClientHtt
 
 	private final int chunkSize;
 
+	@Nullable
 	private OutputStream body;
 
 	private final boolean outputStreaming;

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

@@ -24,6 +24,7 @@ import java.net.URISyntaxException;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StreamUtils;
 
 /**
@@ -40,6 +41,7 @@ final class SimpleStreamingClientHttpRequest extends AbstractClientHttpRequest {
 
 	private final int chunkSize;
 
+	@Nullable
 	private OutputStream body;
 
 	private final boolean outputStreaming;

spring-web/src/main/java/org/springframework/http/codec/AbstractCodecConfigurer.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.http.codec;
 
 import java.util.ArrayList;
@@ -35,10 +36,10 @@ import org.springframework.http.codec.json.Jackson2JsonDecoder;
 import org.springframework.http.codec.json.Jackson2JsonEncoder;
 import org.springframework.http.codec.xml.Jaxb2XmlDecoder;
 import org.springframework.http.codec.xml.Jaxb2XmlEncoder;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
-
 /**
  * Default implementation of {@link CodecConfigurer}.
  *
@@ -63,7 +64,7 @@ abstract class AbstractCodecConfigurer implements CodecConfigurer {
 
 
 	protected AbstractCodecConfigurer(AbstractDefaultCodecs defaultCodecs) {
-		Assert.notNull(defaultCodecs, "'defaultCodecs' is required.");
+		Assert.notNull(defaultCodecs, "'defaultCodecs' is required");
 		this.defaultCodecs = defaultCodecs;
 		this.defaultCodecs.setCustomCodecs(this.customCodecs);
 	}
@@ -117,13 +118,15 @@ abstract class AbstractCodecConfigurer implements CodecConfigurer {
 
 		private boolean registerDefaults = true;
 
+		@Nullable
 		private Jackson2JsonDecoder jackson2Decoder;
 
+		@Nullable
 		private Jackson2JsonEncoder jackson2Encoder;
 
+		@Nullable
 		private DefaultCustomCodecs customCodecs;
 
-
 		public void setRegisterDefaults(boolean registerDefaults) {
 			this.registerDefaults = registerDefaults;
 		}
@@ -139,6 +142,7 @@ abstract class AbstractCodecConfigurer implements CodecConfigurer {
 			this.customCodecs = customCodecs;
 		}
 
+		@Nullable
 		public DefaultCustomCodecs getCustomCodecs() {
 			return this.customCodecs;
 		}
@@ -149,7 +153,7 @@ abstract class AbstractCodecConfigurer implements CodecConfigurer {
 		}
 
 		protected Jackson2JsonDecoder jackson2Decoder() {
-			return this.jackson2Decoder != null ? this.jackson2Decoder : new Jackson2JsonDecoder();
+			return (this.jackson2Decoder != null ? this.jackson2Decoder : new Jackson2JsonDecoder());
 		}
 
 		@Override
@@ -158,7 +162,7 @@ abstract class AbstractCodecConfigurer implements CodecConfigurer {
 		}
 
 		protected Jackson2JsonEncoder jackson2Encoder() {
-			return this.jackson2Encoder != null ? this.jackson2Encoder : new Jackson2JsonEncoder();
+			return (this.jackson2Encoder != null ? this.jackson2Encoder : new Jackson2JsonEncoder());
 		}
 
 		// Readers...
@@ -244,11 +248,12 @@ abstract class AbstractCodecConfigurer implements CodecConfigurer {
 	protected static class DefaultCustomCodecs implements CustomCodecs {
 
 		private final List<HttpMessageReader<?>> typedReaders = new ArrayList<>();
+
 		private final List<HttpMessageWriter<?>> typedWriters = new ArrayList<>();
 
 		private final List<HttpMessageReader<?>> objectReaders = new ArrayList<>();
-		private final List<HttpMessageWriter<?>> objectWriters = new ArrayList<>();
 
+		private final List<HttpMessageWriter<?>> objectWriters = new ArrayList<>();
 
 		@Override
 		public void decoder(Decoder<?> decoder) {
@@ -272,7 +277,6 @@ abstract class AbstractCodecConfigurer implements CodecConfigurer {
 			(canWriteObject ? this.objectWriters : this.typedWriters).add(writer);
 		}
 
-
 		public List<HttpMessageReader<?>> getTypedReaders() {
 			return this.typedReaders;
 		}

spring-web/src/main/java/org/springframework/http/codec/DefaultClientCodecConfigurer.java

@@ -23,6 +23,7 @@ import java.util.List;
 import org.springframework.core.codec.Decoder;
 import org.springframework.core.codec.Encoder;
 import org.springframework.http.codec.multipart.MultipartHttpMessageWriter;
+import org.springframework.lang.Nullable;
 
 /**
  * Default implementation of {@link ClientCodecConfigurer}.
@@ -32,26 +33,24 @@ import org.springframework.http.codec.multipart.MultipartHttpMessageWriter;
  */
 class DefaultClientCodecConfigurer extends AbstractCodecConfigurer implements ClientCodecConfigurer {
 
-
 	public DefaultClientCodecConfigurer() {
 		super(new ClientDefaultCodecsImpl());
 	}
 
-
 	@Override
 	public ClientDefaultCodecs defaultCodecs() {
 		return (ClientDefaultCodecs) super.defaultCodecs();
 	}
 
 
-	private static class ClientDefaultCodecsImpl extends AbstractDefaultCodecs
-			implements ClientDefaultCodecs {
+	private static class ClientDefaultCodecsImpl extends AbstractDefaultCodecs implements ClientDefaultCodecs {
 
+		@Nullable
 		private DefaultMultipartCodecs multipartCodecs;
 
+		@Nullable
 		private Decoder<?> sseDecoder;
 
-
 		@Override
 		public MultipartCodecs multipartCodecs() {
 			if (this.multipartCodecs == null) {
@@ -65,7 +64,6 @@ class DefaultClientCodecConfigurer extends AbstractCodecConfigurer implements Cl
 			this.sseDecoder = decoder;
 		}
 
-
 		@Override
 		protected boolean splitTextOnNewLine() {
 			return false;
@@ -105,22 +103,27 @@ class DefaultClientCodecConfigurer extends AbstractCodecConfigurer implements Cl
 				partWriters = this.multipartCodecs.getWriters();
 			}
 			else {
+				DefaultCustomCodecs customCodecs = getCustomCodecs();
 				partWriters = new ArrayList<>();
 				partWriters.addAll(super.getTypedWriters());
-				partWriters.addAll(getCustomCodecs().getTypedWriters());
+				if (customCodecs != null) {
+					partWriters.addAll(customCodecs.getTypedWriters());
+				}
 				partWriters.addAll(super.getObjectWriters());
-				partWriters.addAll(getCustomCodecs().getObjectWriters());
+				if (customCodecs != null) {
+					partWriters.addAll(customCodecs.getObjectWriters());
+				}
 				partWriters.addAll(super.getCatchAllWriters());
 			}
 			return new MultipartHttpMessageWriter(partWriters);
 		}
 	}
 
+
 	private static class DefaultMultipartCodecs implements MultipartCodecs {
 
 		private final List<HttpMessageWriter<?>> writers = new ArrayList<>();
 
-
 		@Override
 		public MultipartCodecs encoder(Encoder<?> encoder) {
 			writer(new EncoderHttpMessageWriter<>(encoder));

spring-web/src/main/java/org/springframework/http/codec/DefaultServerCodecConfigurer.java

@@ -22,6 +22,7 @@ import java.util.List;
 import org.springframework.core.codec.Encoder;
 import org.springframework.http.codec.multipart.MultipartHttpMessageReader;
 import org.springframework.http.codec.multipart.SynchronossPartHttpMessageReader;
+import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -32,16 +33,15 @@ import org.springframework.util.ClassUtils;
  */
 class DefaultServerCodecConfigurer extends AbstractCodecConfigurer implements ServerCodecConfigurer {
 
-	static final boolean synchronossMultipartPresent =
-			ClassUtils.isPresent("org.synchronoss.cloud.nio.multipart.NioMultipartParser",
-					AbstractCodecConfigurer.class.getClassLoader());
+	static final boolean synchronossMultipartPresent = ClassUtils.isPresent(
+			"org.synchronoss.cloud.nio.multipart.NioMultipartParser",
+			DefaultServerCodecConfigurer.class.getClassLoader());
 
 
 	public DefaultServerCodecConfigurer() {
 		super(new ServerDefaultCodecsImpl());
 	}
 
-
 	@Override
 	public ServerDefaultCodecs defaultCodecs() {
 		return (ServerDefaultCodecs) super.defaultCodecs();
@@ -51,18 +51,16 @@ class DefaultServerCodecConfigurer extends AbstractCodecConfigurer implements Se
 	/**
 	 * Default implementation of {@link ServerDefaultCodecs}.
 	 */
-	private static class ServerDefaultCodecsImpl extends AbstractDefaultCodecs
-			implements ServerDefaultCodecs {
+	private static class ServerDefaultCodecsImpl extends AbstractDefaultCodecs implements ServerDefaultCodecs {
 
+		@Nullable
 		private Encoder<?> sseEncoder;
 
-
 		@Override
 		public void serverSentEventEncoder(Encoder<?> encoder) {
 			this.sseEncoder = encoder;
 		}
 
-
 		@Override
 		protected boolean splitTextOnNewLine() {
 			return true;

spring-web/src/main/java/org/springframework/http/codec/EncoderHttpMessageWriter.java

@@ -35,7 +35,6 @@ import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
-
 /**
  * {@code HttpMessageWriter} that wraps and delegates to a {@link Encoder}.
  *
@@ -54,6 +53,7 @@ public class EncoderHttpMessageWriter<T> implements HttpMessageWriter<T> {
 
 	private final List<MediaType> mediaTypes;
 
+	@Nullable
 	private final MediaType defaultMediaType;
 
 

spring-web/src/main/java/org/springframework/http/codec/ServerCodecConfigurer.java

@@ -34,7 +34,6 @@ import org.springframework.core.codec.Encoder;
  */
 public interface ServerCodecConfigurer extends CodecConfigurer {
 
-
 	@Override
 	ServerDefaultCodecs defaultCodecs();
 

spring-web/src/main/java/org/springframework/http/codec/ServerSentEvent.java

@@ -36,18 +36,25 @@ import org.springframework.lang.Nullable;
  */
 public class ServerSentEvent<T> {
 
+	@Nullable
     private final String id;
 
+	@Nullable
     private final String event;
 
+	@Nullable
     private final Duration retry;
 
+	@Nullable
     private final String comment;
 
+	@Nullable
 	private final T data;
 
 
-    private ServerSentEvent(String id, String event, Duration retry, String comment, T data) {
+    private ServerSentEvent(@Nullable String id, @Nullable String event, @Nullable Duration retry,
+			@Nullable String comment, @Nullable T data) {
+
         this.id = id;
         this.event = event;
         this.retry = retry;
@@ -167,7 +174,7 @@ public class ServerSentEvent<T> {
 		 * @param data the value of the data field
 		 * @return {@code this} builder
 		 */
-		Builder<T> data(T data);
+		Builder<T> data(@Nullable T data);
 
         /**
          * Builds the event.
@@ -179,14 +186,19 @@ public class ServerSentEvent<T> {
 
     private static class BuilderImpl<T> implements Builder<T> {
 
+		@Nullable
         private String id;
 
+		@Nullable
         private String event;
 
+		@Nullable
         private Duration retry;
 
+		@Nullable
         private String comment;
 
+		@Nullable
 		private T data;
 
 		public BuilderImpl() {
@@ -221,7 +233,7 @@ public class ServerSentEvent<T> {
         }
 
 		@Override
-		public Builder<T> data(T data) {
+		public Builder<T> data(@Nullable T data) {
 			this.data = data;
 			return this;
 		}

spring-web/src/main/java/org/springframework/http/codec/ServerSentEventHttpMessageReader.java

@@ -29,6 +29,7 @@ import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
 import org.springframework.core.ResolvableType;
+import org.springframework.core.codec.CodecException;
 import org.springframework.core.codec.Decoder;
 import org.springframework.core.codec.StringDecoder;
 import org.springframework.core.io.buffer.DataBuffer;
@@ -39,12 +40,11 @@ import org.springframework.http.MediaType;
 import org.springframework.http.ReactiveHttpInputMessage;
 import org.springframework.lang.Nullable;
 
-import static java.util.stream.Collectors.joining;
+import static java.util.stream.Collectors.*;
 
 /**
  * Reader that supports a stream of {@link ServerSentEvent}s and also plain
- * {@link Object}s which is the same as an {@link ServerSentEvent} with data
- * only.
+ * {@link Object}s which is the same as an {@link ServerSentEvent} with data only.
  *
  * @author Sebastien Deleuze
  * @author Rossen Stoyanchev
@@ -59,6 +59,7 @@ public class ServerSentEventHttpMessageReader implements HttpMessageReader<Objec
 	private static final StringDecoder stringDecoder = StringDecoder.textPlainOnly(false);
 
 
+	@Nullable
 	private final Decoder<?> decoder;
 
 
@@ -178,11 +179,16 @@ public class ServerSentEventHttpMessageReader implements HttpMessageReader<Objec
 		return sseBuilder.build();
 	}
 
+	@Nullable
 	private Object decodeData(String data, ResolvableType dataType, Map<String, Object> hints) {
 		if (String.class == dataType.resolve()) {
 			return data.substring(0, data.length() - 1);
 		}
 
+		if (this.decoder == null) {
+			return Flux.error(new CodecException("No SSE decoder configured and the data is not String."));
+		}
+
 		byte[] bytes = data.getBytes(StandardCharsets.UTF_8);
 		Mono<DataBuffer> input = Mono.just(bufferFactory.wrap(bytes));
 

spring-web/src/main/java/org/springframework/http/codec/ServerSentEventHttpMessageWriter.java

@@ -48,10 +48,9 @@ import org.springframework.lang.Nullable;
  */
 public class ServerSentEventHttpMessageWriter implements HttpMessageWriter<Object> {
 
-	private static final List<MediaType> WRITABLE_MEDIA_TYPES =
-			Collections.singletonList(MediaType.TEXT_EVENT_STREAM);
-
+	private static final List<MediaType> WRITABLE_MEDIA_TYPES = Collections.singletonList(MediaType.TEXT_EVENT_STREAM);
 
+	@Nullable
 	private final Encoder<?> encoder;
 
 

spring-web/src/main/java/org/springframework/http/codec/multipart/MultipartHttpMessageWriter.java

@@ -230,6 +230,7 @@ public class MultipartHttpMessageWriter implements HttpMessageWriter<MultiValueM
 
 		private final AtomicBoolean committed = new AtomicBoolean();
 
+		@Nullable
 		private Flux<DataBuffer> body;
 
 		public MultipartHttpOutputMessage(DataBufferFactory bufferFactory, Charset charset) {

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

@@ -70,8 +70,10 @@ public class BufferedImageHttpMessageConverter implements HttpMessageConverter<B
 
 	private final List<MediaType> readableMediaTypes = new ArrayList<>();
 
+	@Nullable
 	private MediaType defaultContentType;
 
+	@Nullable
 	private File cacheDir;
 
 
@@ -112,6 +114,7 @@ public class BufferedImageHttpMessageConverter implements HttpMessageConverter<B
 	 * Returns the default {@code Content-Type} to be used for writing.
 	 * Called when {@link #write} is invoked without a specified content type parameter.
 	 */
+	@Nullable
 	public MediaType getDefaultContentType() {
 		return this.defaultContentType;
 	}

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

@@ -100,6 +100,7 @@ public class FormHttpMessageConverter implements HttpMessageConverter<MultiValue
 
 	private Charset charset = DEFAULT_CHARSET;
 
+	@Nullable
 	private Charset multipartCharset;
 
 
@@ -365,7 +366,7 @@ public class FormHttpMessageConverter implements HttpMessageConverter<MultiValue
 	 * we encode directly using the configured {@link #setCharset(Charset)}.
 	 */
 	private boolean isFilenameCharsetSet() {
-		return this.multipartCharset != null;
+		return (this.multipartCharset != null);
 	}
 
 	private void writeParts(OutputStream os, MultiValueMap<String, Object> parts, byte[] boundary) throws IOException {

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

@@ -45,6 +45,7 @@ public class StringHttpMessageConverter extends AbstractHttpMessageConverter<Str
 	public static final Charset DEFAULT_CHARSET = StandardCharsets.ISO_8859_1;
 
 
+	@Nullable
 	private volatile List<Charset> availableCharsets;
 
 	private boolean writeAcceptCharset = true;
@@ -110,11 +111,12 @@ public class StringHttpMessageConverter extends AbstractHttpMessageConverter<Str
 	 * @return the list of accepted charsets
 	 */
 	protected List<Charset> getAcceptedCharsets() {
-		if (this.availableCharsets == null) {
-			this.availableCharsets = new ArrayList<>(
-					Charset.availableCharsets().values());
+		List<Charset> charsets = this.availableCharsets;
+		if (charsets == null) {
+			charsets = new ArrayList<>(Charset.availableCharsets().values());
+			this.availableCharsets = charsets;
 		}
-		return this.availableCharsets;
+		return charsets;
 	}
 
 	private Charset getContentTypeCharset(@Nullable MediaType contentType) {

spring-web/src/main/java/org/springframework/http/converter/json/AbstractJackson2HttpMessageConverter.java

@@ -71,8 +71,10 @@ public abstract class AbstractJackson2HttpMessageConverter extends AbstractGener
 
 	protected ObjectMapper objectMapper;
 
+	@Nullable
 	private Boolean prettyPrint;
 
+	@Nullable
 	private PrettyPrinter ssePrettyPrinter;
 
 
@@ -119,6 +121,7 @@ public abstract class AbstractJackson2HttpMessageConverter extends AbstractGener
 	/**
 	 * Return the underlying {@code ObjectMapper} for this view.
 	 */
+	@Nullable
 	public ObjectMapper getObjectMapper() {
 		return this.objectMapper;
 	}

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

@@ -52,6 +52,7 @@ public abstract class AbstractJsonHttpMessageConverter extends AbstractGenericHt
 
 	public static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;
 
+	@Nullable
 	private String jsonPrefix;
 
 

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

@@ -23,6 +23,7 @@ import com.google.gson.GsonBuilder;
 
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.lang.Nullable;
 
 /**
  * A {@link FactoryBean} for creating a Google Gson 2.x {@link Gson} instance.
@@ -41,8 +42,10 @@ public class GsonFactoryBean implements FactoryBean<Gson>, InitializingBean {
 
 	private boolean disableHtmlEscaping = false;
 
+	@Nullable
 	private String dateFormatPattern;
 
+	@Nullable
 	private Gson gson;
 
 

spring-web/src/main/java/org/springframework/http/converter/json/Jackson2ObjectMapperBuilder.java

@@ -59,6 +59,7 @@ import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.FatalBeanException;
 import org.springframework.context.ApplicationContext;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StreamUtils;
@@ -107,26 +108,37 @@ public class Jackson2ObjectMapperBuilder {
 
 	private boolean createXmlMapper = false;
 
+	@Nullable
 	private JsonFactory factory;
 
+	@Nullable
 	private DateFormat dateFormat;
 
+	@Nullable
 	private Locale locale;
 
+	@Nullable
 	private TimeZone timeZone;
 
+	@Nullable
 	private AnnotationIntrospector annotationIntrospector;
 
+	@Nullable
 	private PropertyNamingStrategy propertyNamingStrategy;
 
+	@Nullable
 	private TypeResolverBuilder<?> defaultTyping;
 
+	@Nullable
 	private JsonInclude.Include serializationInclusion;
 
+	@Nullable
 	private FilterProvider filters;
 
+	@Nullable
 	private List<Module> modules;
 
+	@Nullable
 	private Class<? extends Module>[] moduleClasses;
 
 	private boolean findModulesViaServiceLoader = false;
@@ -135,10 +147,13 @@ public class Jackson2ObjectMapperBuilder {
 
 	private ClassLoader moduleClassLoader = getClass().getClassLoader();
 
+	@Nullable
 	private HandlerInstantiator handlerInstantiator;
 
+	@Nullable
 	private ApplicationContext applicationContext;
 
+	@Nullable
 	private Boolean defaultUseWrapper;
 
 

spring-web/src/main/java/org/springframework/http/converter/json/Jackson2ObjectMapperFactoryBean.java

@@ -46,6 +46,7 @@ import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
+import org.springframework.lang.Nullable;
 
 /**
  * A {@link FactoryBean} for creating a Jackson 2.x {@link ObjectMapper} (default) or
@@ -144,6 +145,7 @@ public class Jackson2ObjectMapperFactoryBean implements FactoryBean<ObjectMapper
 
 	private final Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
 
+	@Nullable
 	private ObjectMapper objectMapper;
 
 

spring-web/src/main/java/org/springframework/http/converter/json/MappingJackson2HttpMessageConverter.java

@@ -22,6 +22,7 @@ import com.fasterxml.jackson.core.JsonGenerator;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
 import org.springframework.http.MediaType;
+import org.springframework.lang.Nullable;
 
 /**
  * Implementation of {@link org.springframework.http.converter.HttpMessageConverter} that can read and
@@ -46,6 +47,7 @@ import org.springframework.http.MediaType;
  */
 public class MappingJackson2HttpMessageConverter extends AbstractJackson2HttpMessageConverter {
 
+	@Nullable
 	private String jsonPrefix;
 
 

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

@@ -36,15 +36,16 @@ public class MappingJacksonInputMessage implements HttpInputMessage {
 
 	private final HttpHeaders headers;
 
+	@Nullable
 	private Class<?> deserializationView;
 
 
-	public MappingJacksonInputMessage(@Nullable InputStream body, HttpHeaders headers) {
+	public MappingJacksonInputMessage(InputStream body, HttpHeaders headers) {
 		this.body = body;
 		this.headers = headers;
 	}
 
-	public MappingJacksonInputMessage(@Nullable InputStream body, HttpHeaders headers, Class<?> deserializationView) {
+	public MappingJacksonInputMessage(InputStream body, HttpHeaders headers, Class<?> deserializationView) {
 		this(body, headers);
 		this.deserializationView = deserializationView;
 	}

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

@@ -74,7 +74,7 @@ public class MappingJacksonValue {
 	 * @see com.fasterxml.jackson.databind.ObjectMapper#writerWithView(Class)
 	 * @see com.fasterxml.jackson.annotation.JsonView
 	 */
-	public void setSerializationView(@Nullable Class<?> serializationView) {
+	public void setSerializationView(Class<?> serializationView) {
 		this.serializationView = serializationView;
 	}
 

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

@@ -91,6 +91,7 @@ public class ProtobufHttpMessageConverter extends AbstractHttpMessageConverter<M
 
 	private final ExtensionRegistry extensionRegistry = ExtensionRegistry.newInstance();
 
+	@Nullable
 	private final ProtobufFormatSupport protobufFormatSupport;
 
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -48,8 +48,10 @@ import org.springframework.util.Assert;
  */
 public class MarshallingHttpMessageConverter extends AbstractXmlHttpMessageConverter<Object> {
 
+	@Nullable
 	private Marshaller marshaller;
 
+	@Nullable
 	private Unmarshaller unmarshaller;
 
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -24,6 +24,7 @@ import javax.servlet.AsyncListener;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -41,6 +42,7 @@ public class ServletServerHttpAsyncRequestControl implements ServerHttpAsyncRequ
 
 	private final ServletServerHttpResponse response;
 
+	@Nullable
 	private AsyncContext asyncContext;
 
 	private AtomicBoolean asyncCompleted = new AtomicBoolean(false);
@@ -101,7 +103,7 @@ public class ServletServerHttpAsyncRequestControl implements ServerHttpAsyncRequ
 
 	@Override
 	public void complete() {
-		if (isStarted() && !isCompleted()) {
+		if (this.asyncContext != null && isStarted() && !isCompleted()) {
 			this.asyncContext.complete();
 		}
 	}

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

@@ -40,6 +40,7 @@ import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.InvalidMediaTypeException;
 import org.springframework.http.MediaType;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.LinkedCaseInsensitiveMap;
 import org.springframework.util.StringUtils;
@@ -60,8 +61,10 @@ public class ServletServerHttpRequest implements ServerHttpRequest {
 
 	private final HttpServletRequest servletRequest;
 
+	@Nullable
 	private HttpHeaders headers;
 
+	@Nullable
 	private ServerHttpAsyncRequestControl asyncRequestControl;
 
 

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

@@ -56,6 +56,7 @@ public abstract class AbstractListenerReadPublisher<T> implements Publisher<T> {
 	private static final AtomicLongFieldUpdater<AbstractListenerReadPublisher> DEMAND_FIELD_UPDATER =
 			AtomicLongFieldUpdater.newUpdater(AbstractListenerReadPublisher.class, "demand");
 
+	@Nullable
 	private Subscriber<? super T> subscriber;
 
 
@@ -126,6 +127,7 @@ public abstract class AbstractListenerReadPublisher<T> implements Publisher<T> {
 				if (r != Long.MAX_VALUE) {
 					DEMAND_FIELD_UPDATER.addAndGet(this, -1L);
 				}
+				Assert.state(this.subscriber != null, "No subscriber");
 				this.subscriber.onNext(data);
 			}
 			else {
@@ -144,7 +146,6 @@ public abstract class AbstractListenerReadPublisher<T> implements Publisher<T> {
 
 		private final AbstractListenerReadPublisher<?> publisher;
 
-
 		public ReadSubscription(AbstractListenerReadPublisher<?> publisher) {
 			this.publisher = publisher;
 		}

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

@@ -26,6 +26,7 @@ import org.reactivestreams.Publisher;
 import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -48,6 +49,7 @@ public abstract class AbstractListenerWriteFlushProcessor<T> implements Processo
 
 	private volatile boolean subscriberCompleted;
 
+	@Nullable
 	private Subscription subscription;
 
 
@@ -105,8 +107,8 @@ public abstract class AbstractListenerWriteFlushProcessor<T> implements Processo
 
 	/**
 	 * Invoked when an error happens while flushing. Defaults to no-op.
-	 * Servlet 3.1 based implementations will receive
-	 * {@link AsyncListener#onError(Throwable)} event.
+	 * Servlet 3.1 based implementations will receive an
+	 * {@link javax.servlet.AsyncListener#onError} event.
 	 */
 	protected void flushingFailed(Throwable t) {
 	}
@@ -185,6 +187,7 @@ public abstract class AbstractListenerWriteFlushProcessor<T> implements Processo
 				}
 				else {
 					if (processor.changeState(this, REQUESTED)) {
+						Assert.state(processor.subscription != null, "No subscription");
 						processor.subscription.request(1);
 					}
 				}

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

@@ -25,6 +25,7 @@ import org.reactivestreams.Processor;
 import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -48,10 +49,12 @@ public abstract class AbstractListenerWriteProcessor<T> implements Processor<T,
 
 	private final AtomicReference<State> state = new AtomicReference<>(State.UNSUBSCRIBED);
 
+	@Nullable
 	protected volatile T currentData;
 
 	private volatile boolean subscriberCompleted;
 
+	@Nullable
 	private Subscription subscription;
 
 
@@ -145,8 +148,8 @@ public abstract class AbstractListenerWriteProcessor<T> implements Processor<T,
 	/**
 	 * Writes the given data to the output.
 	 * @param data the data to write
-	 * @return whether the data was fully written (true)and new data can be
-	 * requested or otherwise (false)
+	 * @return whether the data was fully written ({@code true})
+	 * and new data can be requested, or otherwise ({@code false})
 	 */
 	protected abstract boolean write(T data) throws IOException;
 
@@ -232,6 +235,7 @@ public abstract class AbstractListenerWriteProcessor<T> implements Processor<T,
 			@Override
 			public <T> void onNext(AbstractListenerWriteProcessor<T> processor, T data) {
 				if (processor.isDataEmpty(data)) {
+					Assert.state(processor.subscription != null, "No subscription");
 					processor.subscription.request(1);
 				}
 				else {
@@ -264,6 +268,7 @@ public abstract class AbstractListenerWriteProcessor<T> implements Processor<T,
 			public <T> void onWritePossible(AbstractListenerWriteProcessor<T> processor) {
 				if (processor.changeState(this, WRITING)) {
 					T data = processor.currentData;
+					Assert.state(data != null, "No data");
 					try {
 						boolean writeCompleted = processor.write(data);
 						if (writeCompleted) {
@@ -271,6 +276,7 @@ public abstract class AbstractListenerWriteProcessor<T> implements Processor<T,
 							if (!processor.subscriberCompleted) {
 								processor.changeState(WRITING, REQUESTED);
 								processor.suspendWriting();
+								Assert.state(processor.subscription != null, "No subscription");
 								processor.subscription.request(1);
 							}
 							else {

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

@@ -23,6 +23,7 @@ import java.util.regex.Pattern;
 
 import org.springframework.http.HttpCookie;
 import org.springframework.http.HttpHeaders;
+import org.springframework.lang.Nullable;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
@@ -45,8 +46,10 @@ public abstract class AbstractServerHttpRequest implements ServerHttpRequest {
 
 	private final HttpHeaders headers;
 
+	@Nullable
 	private MultiValueMap<String, String> queryParams;
 
+	@Nullable
 	private MultiValueMap<String, HttpCookie> cookies;
 
 

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

@@ -62,12 +62,14 @@ public abstract class AbstractServerHttpResponse implements ServerHttpResponse {
 
 	private final DataBufferFactory dataBufferFactory;
 
+	@Nullable
 	private HttpStatus statusCode;
 
 	private final HttpHeaders headers;
 
 	private final MultiValueMap<String, ResponseCookie> cookies;
 
+	@Nullable
 	private Function<String, String> urlEncoder = url -> url;
 
 	private final AtomicReference<State> state = new AtomicReference<>(State.NEW);
@@ -105,6 +107,7 @@ public abstract class AbstractServerHttpResponse implements ServerHttpResponse {
 	}
 
 	@Override
+	@Nullable
 	public HttpStatus getStatusCode() {
 		return this.statusCode;
 	}

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

@@ -45,7 +45,8 @@ import org.springframework.util.Assert;
 public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 
 	private final Function<Publisher<T>, Publisher<Void>> writeFunction;
-	private final Flux<T>                                 source;
+
+	private final Flux<T> source;
 
 
 	public ChannelSendOperator(Publisher<? extends T> source, Function<Publisher<T>, Publisher<Void>> writeFunction) {
@@ -53,16 +54,20 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		this.writeFunction = writeFunction;
 	}
 
+
 	@Override
 	@Nullable
 	@SuppressWarnings("rawtypes")
 	public Object scanUnsafe(Attr key) {
-		if (key == IntAttr.PREFETCH) return Integer.MAX_VALUE;
-		if (key == ScannableAttr.PARENT) return source;
+		if (key == IntAttr.PREFETCH) {
+			return Integer.MAX_VALUE;
+		}
+		if (key == ScannableAttr.PARENT) {
+			return this.source;
+		}
 		return null;
 	}
 
-
 	@Override
 	public void subscribe(Subscriber<? super Void> s, Context ctx) {
 		this.source.subscribe(new WriteWithBarrier(s), ctx);
@@ -83,15 +88,18 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		private boolean beforeFirstEmission = true;
 
 		/** Cached signal before readyToWrite */
+		@Nullable
 		private T item;
 
 		/** Cached 1st/2nd signal before readyToWrite */
+		@Nullable
 		private Throwable error;
 
 		/** Cached 1st/2nd signal before readyToWrite */
 		private boolean completed = false;
 
 		/** The actual writeSubscriber vs the downstream completion subscriber */
+		@Nullable
 		private Subscriber<? super T> writeSubscriber;
 
 		public WriteWithBarrier(Subscriber<? super Void> subscriber) {
@@ -107,12 +115,12 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		@Override
 		public void doNext(T item) {
 			if (this.readyToWrite) {
-				this.writeSubscriber.onNext(item);
+				obtainWriteSubscriber().onNext(item);
 				return;
 			}
 			synchronized (this) {
 				if (this.readyToWrite) {
-					this.writeSubscriber.onNext(item);
+					obtainWriteSubscriber().onNext(item);
 				}
 				else if (this.beforeFirstEmission) {
 					this.item = item;
@@ -120,7 +128,9 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 					writeFunction.apply(this).subscribe(new DownstreamBridge(downstream()));
 				}
 				else {
-					subscription.cancel();
+					if (this.subscription != null) {
+						this.subscription.cancel();
+					}
 					downstream().onError(new IllegalStateException("Unexpected item."));
 				}
 			}
@@ -129,12 +139,12 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		@Override
 		public void doError(Throwable ex) {
 			if (this.readyToWrite) {
-				this.writeSubscriber.onError(ex);
+				obtainWriteSubscriber().onError(ex);
 				return;
 			}
 			synchronized (this) {
 				if (this.readyToWrite) {
-					this.writeSubscriber.onError(ex);
+					obtainWriteSubscriber().onError(ex);
 				}
 				else if (this.beforeFirstEmission) {
 					this.beforeFirstEmission = false;
@@ -149,12 +159,12 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		@Override
 		public void doComplete() {
 			if (this.readyToWrite) {
-				this.writeSubscriber.onComplete();
+				obtainWriteSubscriber().onComplete();
 				return;
 			}
 			synchronized (this) {
 				if (this.readyToWrite) {
-					this.writeSubscriber.onComplete();
+					obtainWriteSubscriber().onComplete();
 				}
 				else if (this.beforeFirstEmission) {
 					this.completed = true;
@@ -170,9 +180,8 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		@Override
 		public void subscribe(Subscriber<? super T> writeSubscriber) {
 			synchronized (this) {
-				Assert.isNull(this.writeSubscriber, "Only one writeSubscriber supported");
+				Assert.state(this.writeSubscriber == null, "Only one write subscriber supported");
 				this.writeSubscriber = writeSubscriber;
-
 				if (this.error != null || this.completed) {
 					this.writeSubscriber.onSubscribe(Operators.emptySubscription());
 					emitCachedSignals();
@@ -189,14 +198,14 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		 */
 		private boolean emitCachedSignals() {
 			if (this.item != null) {
-				this.writeSubscriber.onNext(this.item);
+				obtainWriteSubscriber().onNext(this.item);
 			}
 			if (this.error != null) {
-				this.writeSubscriber.onError(this.error);
+				obtainWriteSubscriber().onError(this.error);
 				return true;
 			}
 			if (this.completed) {
-				this.writeSubscriber.onComplete();
+				obtainWriteSubscriber().onComplete();
 				return true;
 			}
 			return false;
@@ -222,13 +231,20 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 				}
 			}
 		}
+
+		private Subscriber<? super T> obtainWriteSubscriber() {
+			Assert.state(this.writeSubscriber != null, "No write subscriber");
+			return this.writeSubscriber;
+		}
 	}
 
+
 	// TODO Remove this copy of Reactor 3.0.x Operators.SubscriberAdapter
 	private static class SubscriberAdapter<I, O> implements Subscriber<I>, Subscription {
 
 		protected final Subscriber<? super O> subscriber;
 
+		@Nullable
 		protected Subscription subscription;
 
 		public SubscriberAdapter(Subscriber<? super O> subscriber) {
@@ -236,15 +252,16 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		}
 
 		public Subscriber<? super O> downstream() {
-			return subscriber;
+			return this.subscriber;
 		}
 
 		@Override
 		public final void cancel() {
 			try {
 				doCancel();
-			} catch (Throwable throwable) {
-				doOnSubscriberError(Operators.onOperatorError(subscription, throwable));
+			}
+			catch (Throwable throwable) {
+				doOnSubscriberError(Operators.onOperatorError(this.subscription, throwable));
 			}
 		}
 
@@ -252,7 +269,8 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		public final void onComplete() {
 			try {
 				doComplete();
-			} catch (Throwable throwable) {
+			}
+			catch (Throwable throwable) {
 				doOnSubscriberError(Operators.onOperatorError(throwable));
 			}
 		}
@@ -268,15 +286,15 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 				doNext(i);
 			}
 			catch (Throwable throwable) {
-				doOnSubscriberError(Operators.onOperatorError(subscription, throwable, i));
+				doOnSubscriberError(Operators.onOperatorError(this.subscription, throwable, i));
 			}
 		}
 
 		@Override
 		public final void onSubscribe(Subscription s) {
-			if (Operators.validate(subscription, s)) {
+			if (Operators.validate(this.subscription, s)) {
 				try {
-					subscription = s;
+					this.subscription = s;
 					doOnSubscribe(s);
 				}
 				catch (Throwable throwable) {
@@ -290,7 +308,8 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 			try {
 				Operators.checkRequest(n);
 				doRequest(n);
-			} catch (Throwable throwable) {
+			}
+			catch (Throwable throwable) {
 				doCancel();
 				doOnSubscriberError(Operators.onOperatorError(throwable));
 			}
@@ -306,28 +325,29 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		 * @param subscription the subscription to optionally process
 		 */
 		protected void doOnSubscribe(Subscription subscription) {
-			subscriber.onSubscribe(this);
+			this.subscriber.onSubscribe(this);
 		}
 
 		public Subscription upstream() {
-			return subscription;
+			Assert.state(this.subscription != null, "No subscription");
+			return this.subscription;
 		}
 
 		@SuppressWarnings("unchecked")
 		protected void doNext(I i) {
-			subscriber.onNext((O) i);
+			this.subscriber.onNext((O) i);
 		}
 
 		protected void doError(Throwable throwable) {
-			subscriber.onError(throwable);
+			this.subscriber.onError(throwable);
 		}
 
 		protected void doOnSubscriberError(Throwable throwable){
-			subscriber.onError(throwable);
+			this.subscriber.onError(throwable);
 		}
 
 		protected void doComplete() {
-			subscriber.onComplete();
+			this.subscriber.onComplete();
 		}
 
 		protected void doRequest(long n) {

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

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.http.server.reactive;
 
 import java.net.URI;
@@ -38,19 +39,19 @@ class DefaultRequestPath implements RequestPath {
 	private final PathSegmentContainer pathWithinApplication;
 
 
-	DefaultRequestPath(URI uri, String contextPath, Charset charset) {
+	DefaultRequestPath(URI uri, @Nullable String contextPath, Charset charset) {
 		this.fullPath = PathSegmentContainer.parse(uri.getRawPath(), charset);
 		this.contextPath = initContextPath(this.fullPath, contextPath);
 		this.pathWithinApplication = extractPathWithinApplication(this.fullPath, this.contextPath);
 	}
 
-	DefaultRequestPath(RequestPath requestPath, String contextPath) {
+	DefaultRequestPath(RequestPath requestPath, @Nullable String contextPath) {
 		this.fullPath = requestPath;
 		this.contextPath = initContextPath(this.fullPath, contextPath);
 		this.pathWithinApplication = extractPathWithinApplication(this.fullPath, this.contextPath);
 	}
 
-	private static PathSegmentContainer initContextPath(PathSegmentContainer path, String contextPath) {
+	private static PathSegmentContainer initContextPath(PathSegmentContainer path, @Nullable String contextPath) {
 		if (!StringUtils.hasText(contextPath) || "/".equals(contextPath)) {
 			return DefaultPathSegmentContainer.EMPTY_PATH;
 		}

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

@@ -36,12 +36,16 @@ class DefaultServerHttpRequestBuilder implements ServerHttpRequest.Builder {
 
 	private final ServerHttpRequest delegate;
 
+	@Nullable
 	private HttpMethod httpMethod;
 
+	@Nullable
 	private String path;
 
+	@Nullable
 	private String contextPath;
 
+	@Nullable
 	private HttpHeaders httpHeaders;
 
 
@@ -103,10 +107,10 @@ class DefaultServerHttpRequestBuilder implements ServerHttpRequest.Builder {
 
 	@Nullable
 	private RequestPath getRequestPathToUse(@Nullable URI uriToUse) {
-		if (uriToUse == null && this.contextPath == null) {
-			return null;
-		}
-		else if (uriToUse == null) {
+		if (uriToUse == null) {
+			if (this.contextPath == null) {
+				return null;
+			}
 			return new DefaultRequestPath(this.delegate.getPath(), this.contextPath);
 		}
 		else {
@@ -134,18 +138,21 @@ class DefaultServerHttpRequestBuilder implements ServerHttpRequest.Builder {
 	 */
 	private static class MutativeDecorator extends ServerHttpRequestDecorator {
 
+		@Nullable
 		private final HttpMethod httpMethod;
 
+		@Nullable
 		private final URI uri;
 
+		@Nullable
 		private final RequestPath requestPath;
 
+		@Nullable
 		private final HttpHeaders httpHeaders;
 
 
-		public MutativeDecorator(ServerHttpRequest delegate, HttpMethod method,
-				@Nullable URI uri, @Nullable RequestPath requestPath,
-				@Nullable HttpHeaders httpHeaders) {
+		public MutativeDecorator(ServerHttpRequest delegate, @Nullable HttpMethod method,
+				@Nullable URI uri, @Nullable RequestPath requestPath, @Nullable HttpHeaders httpHeaders) {
 
 			super(delegate);
 			this.httpMethod = method;

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

@@ -39,6 +39,7 @@ import org.springframework.core.io.buffer.DataBufferUtils;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseCookie;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -53,8 +54,10 @@ public class ServletServerHttpResponse extends AbstractListenerServerHttpRespons
 
 	private final int bufferSize;
 
+	@Nullable
 	private volatile ResponseBodyFlushProcessor bodyFlushProcessor;
 
+	@Nullable
 	private volatile ResponseBodyProcessor bodyProcessor;
 
 	private volatile boolean flushOnNext;
@@ -249,8 +252,9 @@ public class ServletServerHttpResponse extends AbstractListenerServerHttpRespons
 		protected Processor<? super DataBuffer, Void> createWriteProcessor() {
 			try {
 				ServletOutputStream outputStream = response.getOutputStream();
-				bodyProcessor = new ResponseBodyProcessor(outputStream);
-				return bodyProcessor;
+				ResponseBodyProcessor processor = new ResponseBodyProcessor(outputStream);
+				bodyProcessor = processor;
+				return processor;
 			}
 			catch (IOException ex) {
 				throw new UncheckedIOException(ex);

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

@@ -33,6 +33,7 @@ import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.http.HttpCookie;
 import org.springframework.http.HttpHeaders;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
@@ -115,6 +116,7 @@ public class UndertowServerHttpRequest extends AbstractServerHttpRequest {
 
 		private final ByteBufferPool byteBufferPool;
 
+		@Nullable
 		private PooledByteBuffer pooledByteBuffer;
 
 		public RequestBodyPublisher(HttpServerExchange exchange, DataBufferFactory bufferFactory) {

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

@@ -40,6 +40,7 @@ import org.springframework.core.io.buffer.DataBufferUtils;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseCookie;
 import org.springframework.http.ZeroCopyHttpOutputMessage;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -55,6 +56,7 @@ public class UndertowServerHttpResponse extends AbstractListenerServerHttpRespon
 
 	private final HttpServerExchange exchange;
 
+	@Nullable
 	private StreamSinkChannel responseChannel;
 
 
@@ -150,6 +152,7 @@ public class UndertowServerHttpResponse extends AbstractListenerServerHttpRespon
 
 		private final StreamSinkChannel channel;
 
+		@Nullable
 		private volatile ByteBuffer byteBuffer;
 
 		public ResponseBodyProcessor(StreamSinkChannel channel) {
@@ -171,14 +174,15 @@ public class UndertowServerHttpResponse extends AbstractListenerServerHttpRespon
 
 		@Override
 		protected boolean write(DataBuffer dataBuffer) throws IOException {
-			if (this.byteBuffer == null) {
+			ByteBuffer buffer = this.byteBuffer;
+			if (buffer == null) {
 				return false;
 			}
 			if (logger.isTraceEnabled()) {
 				logger.trace("write: " + dataBuffer);
 			}
-			int total = this.byteBuffer.remaining();
-			int written = writeByteBuffer(this.byteBuffer);
+			int total = buffer.remaining();
+			int written = writeByteBuffer(buffer);
 
 			if (logger.isTraceEnabled()) {
 				logger.trace("written: " + written + " total: " + total);

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

@@ -25,6 +25,7 @@ import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
 import reactor.core.publisher.Operators;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -40,10 +41,12 @@ class WriteResultPublisher implements Publisher<Void> {
 
 	private final AtomicReference<State> state = new AtomicReference<>(State.UNSUBSCRIBED);
 
+	@Nullable
 	private Subscriber<? super Void> subscriber;
 
 	private volatile boolean publisherCompleted;
 
+	@Nullable
 	private volatile Throwable publisherError;
 
 
@@ -123,8 +126,11 @@ class WriteResultPublisher implements Publisher<Void> {
 					if (publisher.publisherCompleted) {
 						publisher.publishComplete();
 					}
-					else if (publisher.publisherError != null) {
-						publisher.publishError(publisher.publisherError);
+					else {
+						Throwable publisherError = publisher.publisherError;
+						if (publisherError != null) {
+							publisher.publishError(publisherError);
+						}
 					}
 				}
 				else {
@@ -149,12 +155,14 @@ class WriteResultPublisher implements Publisher<Void> {
 			@Override
 			void publishComplete(WriteResultPublisher publisher) {
 				if (publisher.changeState(this, COMPLETED)) {
+					Assert.state(publisher.subscriber != null, "No subscriber");
 					publisher.subscriber.onComplete();
 				}
 			}
 			@Override
 			void publishError(WriteResultPublisher publisher, Throwable t) {
 				if (publisher.changeState(this, COMPLETED)) {
+					Assert.state(publisher.subscriber != null, "No subscriber");
 					publisher.subscriber.onError(t);
 				}
 			}

spring-web/src/main/java/org/springframework/remoting/caucho/HessianClientInterceptor.java

@@ -68,6 +68,7 @@ public class HessianClientInterceptor extends UrlBasedRemoteAccessor implements
 
 	private HessianProxyFactory proxyFactory = new HessianProxyFactory();
 
+	@Nullable
 	private Object hessianProxy;
 
 

spring-web/src/main/java/org/springframework/remoting/caucho/HessianExporter.java

@@ -62,10 +62,13 @@ public class HessianExporter extends RemoteExporter implements InitializingBean
 
 	private SerializerFactory serializerFactory = new SerializerFactory();
 
+	@Nullable
 	private HessianRemoteResolver remoteResolver;
 
+	@Nullable
 	private Log debugLogger;
 
+	@Nullable
 	private HessianSkeleton skeleton;
 
 
@@ -212,10 +215,8 @@ public class HessianExporter extends RemoteExporter implements InitializingBean
 				throw new IOException("Expected 'H'/'C' (Hessian 2.0) or 'c' (Hessian 1.0) in hessian input at " + code);
 			}
 
-			if (this.serializerFactory != null) {
-				in.setSerializerFactory(this.serializerFactory);
-				out.setSerializerFactory(this.serializerFactory);
-			}
+			in.setSerializerFactory(this.serializerFactory);
+			out.setSerializerFactory(this.serializerFactory);
 			if (this.remoteResolver != null) {
 				in.setRemoteResolver(this.remoteResolver);
 			}

spring-web/src/main/java/org/springframework/remoting/httpinvoker/HttpComponentsHttpInvokerRequestExecutor.java

@@ -73,6 +73,7 @@ public class HttpComponentsHttpInvokerRequestExecutor extends AbstractHttpInvoke
 
 	private HttpClient httpClient;
 
+	@Nullable
 	private RequestConfig requestConfig;
 
 

spring-web/src/main/java/org/springframework/remoting/httpinvoker/HttpInvokerClientInterceptor.java

@@ -73,8 +73,10 @@ import org.springframework.remoting.support.RemoteInvocationResult;
 public class HttpInvokerClientInterceptor extends RemoteInvocationBasedAccessor
 		implements MethodInterceptor, HttpInvokerClientConfiguration {
 
+	@Nullable
 	private String codebaseUrl;
 
+	@Nullable
 	private HttpInvokerRequestExecutor httpInvokerRequestExecutor;
 
 
@@ -98,6 +100,7 @@ public class HttpInvokerClientInterceptor extends RemoteInvocationBasedAccessor
 	 * Return the codebase URL to download classes from if not found locally.
 	 */
 	@Override
+	@Nullable
 	public String getCodebaseUrl() {
 		return this.codebaseUrl;
 	}

spring-web/src/main/java/org/springframework/remoting/jaxws/AbstractJaxWsServiceExporter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -33,6 +33,8 @@ import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.beans.factory.ListableBeanFactory;
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * Abstract exporter for JAX-WS services, autodetecting annotated service beans
@@ -50,14 +52,19 @@ import org.springframework.beans.factory.config.ConfigurableBeanFactory;
  */
 public abstract class AbstractJaxWsServiceExporter implements BeanFactoryAware, InitializingBean, DisposableBean {
 
+	@Nullable
 	private Map<String, Object> endpointProperties;
 
+	@Nullable
 	private Executor executor;
 
+	@Nullable
 	private String bindingType;
 
+	@Nullable
 	private WebServiceFeature[] endpointFeatures;
 
+	@Nullable
 	private ListableBeanFactory beanFactory;
 
 	private final Set<Endpoint> publishedEndpoints = new LinkedHashSet<>();
@@ -127,11 +134,14 @@ public abstract class AbstractJaxWsServiceExporter implements BeanFactoryAware,
 	 * @see #publishEndpoint
 	 */
 	public void publishEndpoints() {
+		Assert.state(this.beanFactory != null, "No BeanFactory set");
+
 		Set<String> beanNames = new LinkedHashSet<>(this.beanFactory.getBeanDefinitionCount());
 		beanNames.addAll(Arrays.asList(this.beanFactory.getBeanDefinitionNames()));
 		if (this.beanFactory instanceof ConfigurableBeanFactory) {
 			beanNames.addAll(Arrays.asList(((ConfigurableBeanFactory) this.beanFactory).getSingletonNames()));
 		}
+
 		for (String beanName : beanNames) {
 			try {
 				Class<?> type = this.beanFactory.getType(beanName);

spring-web/src/main/java/org/springframework/remoting/jaxws/JaxWsPortClientInterceptor.java

@@ -65,34 +65,46 @@ import org.springframework.util.StringUtils;
 public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 		implements MethodInterceptor, BeanClassLoaderAware, InitializingBean {
 
+	@Nullable
 	private Service jaxWsService;
 
+	@Nullable
 	private String portName;
 
+	@Nullable
 	private String username;
 
+	@Nullable
 	private String password;
 
+	@Nullable
 	private String endpointAddress;
 
 	private boolean maintainSession;
 
 	private boolean useSoapAction;
 
+	@Nullable
 	private String soapActionUri;
 
+	@Nullable
 	private Map<String, Object> customProperties;
 
+	@Nullable
 	private WebServiceFeature[] portFeatures;
 
+	@Nullable
 	private Class<?> serviceInterface;
 
 	private boolean lookupServiceOnStartup = true;
 
+	@Nullable
 	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
 
+	@Nullable
 	private QName portQName;
 
+	@Nullable
 	private Object portStub;
 
 	private final Object preparationMonitor = new Object();
@@ -286,6 +298,7 @@ public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 	/**
 	 * Return the interface of the service that this factory should create a proxy for.
 	 */
+	@Nullable
 	public Class<?> getServiceInterface() {
 		return this.serviceInterface;
 	}
@@ -312,6 +325,7 @@ public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 	/**
 	 * Return the bean ClassLoader to use for this interceptor.
 	 */
+	@Nullable
 	protected ClassLoader getBeanClassLoader() {
 		return this.beanClassLoader;
 	}
@@ -402,6 +416,7 @@ public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 	 * @see #setPortName
 	 * @see #getQName
 	 */
+	@Nullable
 	protected final QName getPortQName() {
 		return this.portQName;
 	}
@@ -472,6 +487,7 @@ public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 	 * Return the underlying JAX-WS port stub that this interceptor delegates to
 	 * for each method invocation on the proxy.
 	 */
+	@Nullable
 	protected Object getPortStub() {
 		return this.portStub;
 	}
@@ -526,7 +542,7 @@ public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 	 * @see #getPortStub()
 	 */
 	@Nullable
-	protected Object doInvoke(MethodInvocation invocation, Object portStub) throws Throwable {
+	protected Object doInvoke(MethodInvocation invocation, @Nullable Object portStub) throws Throwable {
 		Method method = invocation.getMethod();
 		try {
 			return method.invoke(portStub, invocation.getArguments());

spring-web/src/main/java/org/springframework/remoting/jaxws/LocalJaxWsServiceFactory.java

@@ -44,16 +44,22 @@ import org.springframework.util.Assert;
  */
 public class LocalJaxWsServiceFactory {
 
+	@Nullable
 	private URL wsdlDocumentUrl;
 
+	@Nullable
 	private String namespaceUri;
 
+	@Nullable
 	private String serviceName;
 
+	@Nullable
 	private WebServiceFeature[] serviceFeatures;
 
+	@Nullable
 	private Executor executor;
 
+	@Nullable
 	private HandlerResolver handlerResolver;
 
 

spring-web/src/main/java/org/springframework/remoting/jaxws/LocalJaxWsServiceFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -20,6 +20,7 @@ import javax.xml.ws.Service;
 
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.lang.Nullable;
 
 /**
  * {@link org.springframework.beans.factory.FactoryBean} for locally
@@ -38,6 +39,7 @@ import org.springframework.beans.factory.InitializingBean;
 public class LocalJaxWsServiceFactoryBean extends LocalJaxWsServiceFactory
 		implements FactoryBean<Service>, InitializingBean {
 
+	@Nullable
 	private Service service;
 
 

spring-web/src/main/java/org/springframework/remoting/jaxws/SimpleHttpServerJaxWsServiceExporter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -29,7 +29,9 @@ import com.sun.net.httpserver.HttpServer;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import org.springframework.lang.Nullable;
 import org.springframework.lang.UsesSunHttpServer;
+import org.springframework.util.Assert;
 
 /**
  * Simple exporter for JAX-WS services, autodetecting annotated service beans
@@ -53,10 +55,12 @@ public class SimpleHttpServerJaxWsServiceExporter extends AbstractJaxWsServiceEx
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private HttpServer server;
 
 	private int port = 8080;
 
+	@Nullable
 	private String hostname;
 
 	private int backlog = -1;
@@ -65,8 +69,10 @@ public class SimpleHttpServerJaxWsServiceExporter extends AbstractJaxWsServiceEx
 
 	private String basePath = "/";
 
+	@Nullable
 	private List<Filter> filters;
 
+	@Nullable
 	private Authenticator authenticator;
 
 	private boolean localServer = false;
@@ -157,11 +163,12 @@ public class SimpleHttpServerJaxWsServiceExporter extends AbstractJaxWsServiceEx
 		if (this.server == null) {
 			InetSocketAddress address = (this.hostname != null ?
 					new InetSocketAddress(this.hostname, this.port) : new InetSocketAddress(this.port));
-			this.server = HttpServer.create(address, this.backlog);
+			HttpServer server = HttpServer.create(address, this.backlog);
 			if (this.logger.isInfoEnabled()) {
 				this.logger.info("Starting HttpServer at address " + address);
 			}
-			this.server.start();
+			server.start();
+			this.server = server;
 			this.localServer = true;
 		}
 		super.afterPropertiesSet();
@@ -184,6 +191,7 @@ public class SimpleHttpServerJaxWsServiceExporter extends AbstractJaxWsServiceEx
 	 * @return the fully populated HttpContext
 	 */
 	protected HttpContext buildHttpContext(Endpoint endpoint, String serviceName) {
+		Assert.state(this.server != null, "No HttpServer available");
 		String fullPath = calculateEndpointPath(endpoint, serviceName);
 		HttpContext httpContext = this.server.createContext(fullPath);
 		if (this.filters != null) {
@@ -209,7 +217,7 @@ public class SimpleHttpServerJaxWsServiceExporter extends AbstractJaxWsServiceEx
 	@Override
 	public void destroy() {
 		super.destroy();
-		if (this.localServer) {
+		if (this.server != null && this.localServer) {
 			logger.info("Stopping HttpServer");
 			this.server.stop(this.shutdownDelay);
 		}

spring-web/src/main/java/org/springframework/web/HttpMediaTypeNotSupportedException.java

@@ -31,6 +31,7 @@ import org.springframework.lang.Nullable;
 @SuppressWarnings("serial")
 public class HttpMediaTypeNotSupportedException extends HttpMediaTypeException {
 
+	@Nullable
 	private final MediaType contentType;
 
 
@@ -67,6 +68,7 @@ public class HttpMediaTypeNotSupportedException extends HttpMediaTypeException {
 	/**
 	 * Return the HTTP request content type method that caused the failure.
 	 */
+	@Nullable
 	public MediaType getContentType() {
 		return this.contentType;
 	}

spring-web/src/main/java/org/springframework/web/HttpRequestMethodNotSupportedException.java

@@ -39,6 +39,7 @@ public class HttpRequestMethodNotSupportedException extends ServletException {
 
 	private String method;
 
+	@Nullable
 	private String[] supportedMethods;
 
 

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

@@ -101,14 +101,18 @@ public class ContentNegotiationManagerFactoryBean
 
 	private boolean ignoreUnknownPathExtensions = true;
 
+	@Nullable
 	private Boolean useRegisteredExtensionsOnly;
 
 	private String parameterName = "format";
 
+	@Nullable
 	private ContentNegotiationStrategy defaultNegotiationStrategy;
 
+	@Nullable
 	private ContentNegotiationManager contentNegotiationManager;
 
+	@Nullable
 	private ServletContext servletContext;
 
 
@@ -268,13 +272,12 @@ public class ContentNegotiationManagerFactoryBean
 	}
 
 
-	public ContentNegotiationManager build() {
-		afterPropertiesSet();
-		return this.contentNegotiationManager;
-	}
-
 	@Override
 	public void afterPropertiesSet() {
+		build();
+	}
+
+	public ContentNegotiationManager build() {
 		List<ContentNegotiationStrategy> strategies = new ArrayList<>();
 
 		if (this.favorPathExtension) {
@@ -309,8 +312,10 @@ public class ContentNegotiationManagerFactoryBean
 		}
 
 		this.contentNegotiationManager = new ContentNegotiationManager(strategies);
+		return this.contentNegotiationManager;
 	}
 
+
 	@Override
 	public ContentNegotiationManager getObject() {
 		return this.contentNegotiationManager;

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

@@ -17,7 +17,6 @@
 package org.springframework.web.accept;
 
 import java.util.Map;
-
 import javax.servlet.ServletContext;
 
 import org.springframework.core.io.Resource;
@@ -72,11 +71,9 @@ public class ServletPathExtensionContentNegotiationStrategy extends PathExtensio
 			throws HttpMediaTypeNotAcceptableException {
 
 		MediaType mediaType = null;
-		if (this.servletContext != null) {
-			String mimeType = this.servletContext.getMimeType("file." + extension);
-			if (StringUtils.hasText(mimeType)) {
-				mediaType = MediaType.parseMediaType(mimeType);
-			}
+		String mimeType = this.servletContext.getMimeType("file." + extension);
+		if (StringUtils.hasText(mimeType)) {
+			mediaType = MediaType.parseMediaType(mimeType);
 		}
 		if (mediaType == null || MediaType.APPLICATION_OCTET_STREAM.equals(mediaType)) {
 			MediaType superMediaType = super.handleNoMatch(webRequest, extension);
@@ -98,11 +95,9 @@ public class ServletPathExtensionContentNegotiationStrategy extends PathExtensio
 	@Override
 	public MediaType getMediaTypeForResource(Resource resource) {
 		MediaType mediaType = null;
-		if (this.servletContext != null) {
-			String mimeType = this.servletContext.getMimeType(resource.getFilename());
-			if (StringUtils.hasText(mimeType)) {
-				mediaType = MediaType.parseMediaType(mimeType);
-			}
+		String mimeType = this.servletContext.getMimeType(resource.getFilename());
+		if (StringUtils.hasText(mimeType)) {
+			mediaType = MediaType.parseMediaType(mimeType);
 		}
 		if (mediaType == null || MediaType.APPLICATION_OCTET_STREAM.equals(mediaType)) {
 			MediaType superMediaType = super.getMediaTypeForResource(resource);

spring-web/src/main/java/org/springframework/web/bind/ServletRequestDataBinder.java

@@ -75,7 +75,7 @@ public class ServletRequestDataBinder extends WebDataBinder {
 	 * if the binder is just used to convert a plain parameter value)
 	 * @param objectName the name of the target object
 	 */
-	public ServletRequestDataBinder(@Nullable Object target, @Nullable String objectName) {
+	public ServletRequestDataBinder(@Nullable Object target, String objectName) {
 		super(target, objectName);
 	}
 

spring-web/src/main/java/org/springframework/web/bind/WebDataBinder.java

@@ -98,7 +98,7 @@ public class WebDataBinder extends DataBinder {
 	 * if the binder is just used to convert a plain parameter value)
 	 * @param objectName the name of the target object
 	 */
-	public WebDataBinder(@Nullable Object target, @Nullable String objectName) {
+	public WebDataBinder(@Nullable Object target, String objectName) {
 		super(target, objectName);
 	}
 

spring-web/src/main/java/org/springframework/web/bind/support/ConfigurableWebBindingInitializer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -44,14 +44,19 @@ public class ConfigurableWebBindingInitializer implements WebBindingInitializer
 
 	private boolean directFieldAccess = false;
 
+	@Nullable
 	private MessageCodesResolver messageCodesResolver;
 
+	@Nullable
 	private BindingErrorProcessor bindingErrorProcessor;
 
+	@Nullable
 	private Validator validator;
 
+	@Nullable
 	private ConversionService conversionService;
 
+	@Nullable
 	private PropertyEditorRegistrar[] propertyEditorRegistrars;
 
 

spring-web/src/main/java/org/springframework/web/bind/support/DefaultDataBinderFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -29,6 +29,7 @@ import org.springframework.web.context.request.NativeWebRequest;
  */
 public class DefaultDataBinderFactory implements WebDataBinderFactory {
 
+	@Nullable
 	private final WebBindingInitializer initializer;
 
 
@@ -49,8 +50,8 @@ public class DefaultDataBinderFactory implements WebDataBinderFactory {
 	 */
 	@Override
 	@SuppressWarnings("deprecation")
-	public final WebDataBinder createBinder(NativeWebRequest webRequest, @Nullable Object target,
-			@Nullable String objectName) throws Exception {
+	public final WebDataBinder createBinder(
+			NativeWebRequest webRequest, @Nullable Object target, String objectName) throws Exception {
 
 		WebDataBinder dataBinder = createBinderInstance(target, objectName, webRequest);
 		if (this.initializer != null) {
@@ -69,7 +70,7 @@ public class DefaultDataBinderFactory implements WebDataBinderFactory {
 	 * @throws Exception in case of invalid state or arguments
 	 */
 	protected WebDataBinder createBinderInstance(
-			@Nullable Object target, @Nullable String objectName, NativeWebRequest webRequest) throws Exception {
+			@Nullable Object target, String objectName, NativeWebRequest webRequest) throws Exception {
 
 		return new WebRequestDataBinder(target, objectName);
 	}

spring-web/src/main/java/org/springframework/web/bind/support/WebDataBinderFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -31,11 +31,13 @@ public interface WebDataBinderFactory {
 	/**
 	 * Create a {@link WebDataBinder} for the given object.
 	 * @param webRequest the current request
-	 * @param target the object to create a data binder for, or {@code null} if creating a binder for a simple type
+	 * @param target the object to create a data binder for,
+	 * or {@code null} if creating a binder for a simple type
 	 * @param objectName the name of the target object
 	 * @return the created {@link WebDataBinder} instance, never null
 	 * @throws Exception raised if the creation and initialization of the data binder fails
 	 */
-	WebDataBinder createBinder(NativeWebRequest webRequest, @Nullable Object target, @Nullable String objectName) throws Exception;
+	WebDataBinder createBinder(NativeWebRequest webRequest, @Nullable Object target, String objectName)
+			throws Exception;
 
 }

spring-web/src/main/java/org/springframework/web/bind/support/WebExchangeDataBinder.java

@@ -41,7 +41,6 @@ import org.springframework.web.server.ServerWebExchange;
  */
 public class WebExchangeDataBinder extends WebDataBinder {
 
-
 	/**
 	 * Create a new instance, with default object name.
 	 * @param target the target object to bind onto (or {@code null} if the
@@ -86,12 +85,10 @@ public class WebExchangeDataBinder extends WebDataBinder {
 	 * Combine query params and form data for multipart form data from the body
 	 * of the request into a {@code Map<String, Object>} of values to use for
 	 * data binding purposes.
-	 *
 	 * @param exchange the current exchange
 	 * @return a {@code Mono} with the values to bind
 	 */
 	public static Mono<Map<String, Object>> extractValuesToBind(ServerWebExchange exchange) {
-
 		MultiValueMap<String, String> queryParams = exchange.getRequest().getQueryParams();
 		Mono<MultiValueMap<String, String>> formData = exchange.getFormData();
 		Mono<MultiValueMap<String, Part>> multipartData = exchange.getMultipartData();

spring-web/src/main/java/org/springframework/web/bind/support/WebRequestDataBinder.java

@@ -86,7 +86,7 @@ public class WebRequestDataBinder extends WebDataBinder {
 	 * if the binder is just used to convert a plain parameter value)
 	 * @param objectName the name of the target object
 	 */
-	public WebRequestDataBinder(@Nullable Object target, @Nullable String objectName) {
+	public WebRequestDataBinder(@Nullable Object target, String objectName) {
 		super(target, objectName);
 	}
 

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

@@ -593,6 +593,7 @@ public class AsyncRestTemplate extends org.springframework.http.client.support.I
 
 		private final URI url;
 
+		@Nullable
 		private final ResponseExtractor<T> responseExtractor;
 
 		public ResponseExtractorFuture(HttpMethod method, URI url,

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

@@ -28,6 +28,7 @@ import org.springframework.http.client.ClientHttpResponse;
 import org.springframework.http.converter.GenericHttpMessageConverter;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.HttpMessageNotReadableException;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -42,6 +43,7 @@ public class HttpMessageConverterExtractor<T> implements ResponseExtractor<T> {
 
 	private final Type responseType;
 
+	@Nullable
 	private final Class<T> responseClass;
 
 	private final List<HttpMessageConverter<?>> messageConverters;

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

@@ -23,6 +23,7 @@ import java.io.PushbackInputStream;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.client.ClientHttpResponse;
+import org.springframework.lang.Nullable;
 
 /**
  * Implementation of {@link ClientHttpResponse} that can not only check if
@@ -31,12 +32,13 @@ import org.springframework.http.client.ClientHttpResponse;
  *
  * @author Brian Clozel
  * @since 4.1.5
- * @see <a href="http://tools.ietf.org/html/rfc7230#section-3.3.3">rfc7230 Section 3.3.3</a>
+ * @see <a href="http://tools.ietf.org/html/rfc7230#section-3.3.3">RFC 7230 Section 3.3.3</a>
  */
 class MessageBodyClientHttpResponseWrapper implements ClientHttpResponse {
 
 	private final ClientHttpResponse response;
 
+	@Nullable
 	private PushbackInputStream pushbackInputStream;
 
 

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

@@ -42,8 +42,10 @@ public class RestClientResponseException extends RestClientException {
 
 	private final byte[] responseBody;
 
+	@Nullable
 	private final HttpHeaders responseHeaders;
 
+	@Nullable
 	private final String responseCharset;
 
 
@@ -84,6 +86,7 @@ public class RestClientResponseException extends RestClientException {
 	/**
 	 * Return the HTTP response headers.
 	 */
+	@Nullable
 	public HttpHeaders getResponseHeaders() {
 		return this.responseHeaders;
 	}

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

@@ -783,6 +783,7 @@ public class RestTemplate extends InterceptingHttpAccessor implements RestOperat
 	 */
 	private class AcceptHeaderRequestCallback implements RequestCallback {
 
+		@Nullable
 		private final Type responseType;
 
 		private AcceptHeaderRequestCallback(@Nullable Type responseType) {
@@ -937,6 +938,7 @@ public class RestTemplate extends InterceptingHttpAccessor implements RestOperat
 	 */
 	private class ResponseEntityResponseExtractor<T> implements ResponseExtractor<ResponseEntity<T>> {
 
+		@Nullable
 		private final HttpMessageConverterExtractor<T> delegate;
 
 		public ResponseEntityResponseExtractor(@Nullable Type responseType) {

spring-web/src/main/java/org/springframework/web/context/ContextLoader.java

@@ -158,12 +158,14 @@ public class ContextLoader {
 	 * The 'current' WebApplicationContext, if the ContextLoader class is
 	 * deployed in the web app ClassLoader itself.
 	 */
+	@Nullable
 	private static volatile WebApplicationContext currentContext;
 
 
 	/**
 	 * The root WebApplicationContext instance that this loader manages.
 	 */
+	@Nullable
 	private WebApplicationContext context;
 
 	/** Actual ApplicationContextInitializer instances to apply to the context */

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -62,8 +62,10 @@ public class ServletRequestAttributes extends AbstractRequestAttributes {
 
 	private final HttpServletRequest request;
 
+	@Nullable
 	private HttpServletResponse response;
 
+	@Nullable
 	private volatile HttpSession session;
 
 	private final Map<String, Object> sessionAttributesToUpdate = new ConcurrentHashMap<>(1);

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

@@ -24,9 +24,11 @@ import org.springframework.context.support.AbstractRefreshableConfigApplicationC
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.support.ResourcePatternResolver;
+import org.springframework.lang.Nullable;
 import org.springframework.ui.context.Theme;
 import org.springframework.ui.context.ThemeSource;
 import org.springframework.ui.context.support.UiApplicationContextUtils;
+import org.springframework.util.Assert;
 import org.springframework.web.context.ConfigurableWebApplicationContext;
 import org.springframework.web.context.ConfigurableWebEnvironment;
 import org.springframework.web.context.ServletConfigAware;
@@ -80,15 +82,19 @@ public abstract class AbstractRefreshableWebApplicationContext extends AbstractR
 		implements ConfigurableWebApplicationContext, ThemeSource {
 
 	/** Servlet context that this context runs in */
+	@Nullable
 	private ServletContext servletContext;
 
 	/** Servlet config that this context runs in, if any */
+	@Nullable
 	private ServletConfig servletConfig;
 
 	/** Namespace of this context, or {@code null} if root */
+	@Nullable
 	private String namespace;
 
 	/** the ThemeSource for this ApplicationContext */
+	@Nullable
 	private ThemeSource themeSource;
 
 
@@ -103,6 +109,7 @@ public abstract class AbstractRefreshableWebApplicationContext extends AbstractR
 	}
 
 	@Override
+	@Nullable
 	public ServletContext getServletContext() {
 		return this.servletContext;
 	}
@@ -116,6 +123,7 @@ public abstract class AbstractRefreshableWebApplicationContext extends AbstractR
 	}
 
 	@Override
+	@Nullable
 	public ServletConfig getServletConfig() {
 		return this.servletConfig;
 	}
@@ -127,6 +135,7 @@ public abstract class AbstractRefreshableWebApplicationContext extends AbstractR
 	}
 
 	@Override
+	@Nullable
 	public String getNamespace() {
 		return this.namespace;
 	}
@@ -169,6 +178,7 @@ public abstract class AbstractRefreshableWebApplicationContext extends AbstractR
 	 */
 	@Override
 	protected Resource getResourceByPath(String path) {
+		Assert.state(this.servletContext != null, "No ServletContext available");
 		return new ServletContextResource(this.servletContext, path);
 	}
 
@@ -203,6 +213,7 @@ public abstract class AbstractRefreshableWebApplicationContext extends AbstractR
 
 	@Override
 	public Theme getTheme(String themeName) {
+		Assert.state(this.themeSource != null, "No ThemeSource available");
 		return this.themeSource.getTheme(themeName);
 	}
 

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

@@ -37,8 +37,10 @@ public class ContextExposingHttpServletRequest extends HttpServletRequestWrapper
 
 	private final WebApplicationContext webApplicationContext;
 
+	@Nullable
 	private final Set<String> exposedContextBeanNames;
 
+	@Nullable
 	private Set<String> explicitAttributes;
 
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -29,6 +29,7 @@ import org.springframework.lang.Nullable;
 import org.springframework.ui.context.Theme;
 import org.springframework.ui.context.ThemeSource;
 import org.springframework.ui.context.support.UiApplicationContextUtils;
+import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.web.context.ConfigurableWebApplicationContext;
@@ -64,8 +65,10 @@ import org.springframework.web.context.ServletContextAware;
 public class GenericWebApplicationContext extends GenericApplicationContext
 		implements ConfigurableWebApplicationContext, ThemeSource {
 
+	@Nullable
 	private ServletContext servletContext;
 
+	@Nullable
 	private ThemeSource themeSource;
 
 
@@ -122,6 +125,7 @@ public class GenericWebApplicationContext extends GenericApplicationContext
 	}
 
 	@Override
+	@Nullable
 	public ServletContext getServletContext() {
 		return this.servletContext;
 	}
@@ -145,9 +149,10 @@ public class GenericWebApplicationContext extends GenericApplicationContext
 	 */
 	@Override
 	protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
-		beanFactory.addBeanPostProcessor(new ServletContextAwareProcessor(this.servletContext));
-		beanFactory.ignoreDependencyInterface(ServletContextAware.class);
-
+		if (this.servletContext != null) {
+			beanFactory.addBeanPostProcessor(new ServletContextAwareProcessor(this.servletContext));
+			beanFactory.ignoreDependencyInterface(ServletContextAware.class);
+		}
 		WebApplicationContextUtils.registerWebApplicationScopes(beanFactory, this.servletContext);
 		WebApplicationContextUtils.registerEnvironmentBeans(beanFactory, this.servletContext);
 	}
@@ -158,6 +163,7 @@ public class GenericWebApplicationContext extends GenericApplicationContext
 	 */
 	@Override
 	protected Resource getResourceByPath(String path) {
+		Assert.state(this.servletContext != null, "No ServletContext available");
 		return new ServletContextResource(this.servletContext, path);
 	}
 
@@ -192,6 +198,7 @@ public class GenericWebApplicationContext extends GenericApplicationContext
 
 	@Override
 	public Theme getTheme(String themeName) {
+		Assert.state(this.themeSource != null, "No ThemeSource available");
 		return this.themeSource.getTheme(themeName);
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -38,15 +38,18 @@ import org.springframework.lang.Nullable;
 public class RequestHandledEvent extends ApplicationEvent {
 
 	/** Session id that applied to the request, if any */
+	@Nullable
 	private String sessionId;
 
 	/** Usually the UserPrincipal */
+	@Nullable
 	private String userName;
 
 	/** Request processing time */
 	private final long processingTimeMillis;
 
 	/** Cause of failure, if any */
+	@Nullable
 	private Throwable failureCause;
 
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -19,6 +19,7 @@ package org.springframework.web.context.support;
 import javax.servlet.ServletContext;
 
 import org.springframework.beans.factory.FactoryBean;
+import org.springframework.lang.Nullable;
 import org.springframework.web.context.ServletContextAware;
 
 /**
@@ -43,8 +44,10 @@ import org.springframework.web.context.ServletContextAware;
  */
 public class ServletContextAttributeFactoryBean implements FactoryBean<Object>, ServletContextAware {
 
+	@Nullable
 	private String attributeName;
 
+	@Nullable
 	private Object attribute;
 
 

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

@@ -41,8 +41,10 @@ import org.springframework.web.context.ServletContextAware;
  */
 public class ServletContextAwareProcessor implements BeanPostProcessor {
 
+	@Nullable
 	private ServletContext servletContext;
 
+	@Nullable
 	private ServletConfig servletConfig;
 
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -19,6 +19,7 @@ package org.springframework.web.context.support;
 import javax.servlet.ServletContext;
 
 import org.springframework.beans.factory.FactoryBean;
+import org.springframework.lang.Nullable;
 import org.springframework.web.context.ServletContextAware;
 
 /**
@@ -38,8 +39,10 @@ import org.springframework.web.context.ServletContextAware;
  */
 public class ServletContextParameterFactoryBean implements FactoryBean<String>, ServletContextAware {
 
+	@Nullable
 	private String initParamName;
 
+	@Nullable
 	private String paramValue;
 
 

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

@@ -24,9 +24,11 @@ import org.springframework.context.support.StaticApplicationContext;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.support.ResourcePatternResolver;
+import org.springframework.lang.Nullable;
 import org.springframework.ui.context.Theme;
 import org.springframework.ui.context.ThemeSource;
 import org.springframework.ui.context.support.UiApplicationContextUtils;
+import org.springframework.util.Assert;
 import org.springframework.web.context.ConfigurableWebApplicationContext;
 import org.springframework.web.context.ServletConfigAware;
 import org.springframework.web.context.ServletContextAware;
@@ -56,12 +58,16 @@ import org.springframework.web.context.ServletContextAware;
 public class StaticWebApplicationContext extends StaticApplicationContext
 		implements ConfigurableWebApplicationContext, ThemeSource {
 
+	@Nullable
 	private ServletContext servletContext;
 
+	@Nullable
 	private ServletConfig servletConfig;
 
+	@Nullable
 	private String namespace;
 
+	@Nullable
 	private ThemeSource themeSource;
 
 
@@ -79,6 +85,7 @@ public class StaticWebApplicationContext extends StaticApplicationContext
 	}
 
 	@Override
+	@Nullable
 	public ServletContext getServletContext() {
 		return this.servletContext;
 	}
@@ -92,6 +99,7 @@ public class StaticWebApplicationContext extends StaticApplicationContext
 	}
 
 	@Override
+	@Nullable
 	public ServletConfig getServletConfig() {
 		return this.servletConfig;
 	}
@@ -103,6 +111,7 @@ public class StaticWebApplicationContext extends StaticApplicationContext
 	}
 
 	@Override
+	@Nullable
 	public String getNamespace() {
 		return this.namespace;
 	}
@@ -150,6 +159,7 @@ public class StaticWebApplicationContext extends StaticApplicationContext
 	 */
 	@Override
 	protected Resource getResourceByPath(String path) {
+		Assert.state(this.servletContext != null, "No ServletContext available");
 		return new ServletContextResource(this.servletContext, path);
 	}
 
@@ -186,6 +196,7 @@ public class StaticWebApplicationContext extends StaticApplicationContext
 
 	@Override
 	public Theme getTheme(String themeName) {
+		Assert.state(this.themeSource != null, "No ThemeSource available");
 		return this.themeSource.getTheme(themeName);
 	}
 

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

@@ -205,7 +205,7 @@ public abstract class WebApplicationContextUtils {
 	 * @param bf the BeanFactory to configure
 	 * @param sc the ServletContext that we're running within
 	 */
-	public static void registerEnvironmentBeans(ConfigurableListableBeanFactory bf, ServletContext sc) {
+	public static void registerEnvironmentBeans(ConfigurableListableBeanFactory bf, @Nullable ServletContext sc) {
 		registerEnvironmentBeans(bf, sc, null);
 	}
 

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

@@ -42,6 +42,7 @@ import org.springframework.web.util.WebUtils;
  */
 public abstract class WebApplicationObjectSupport extends ApplicationObjectSupport implements ServletContextAware {
 
+	@Nullable
 	private ServletContext servletContext;
 
 

spring-web/src/main/java/org/springframework/web/cors/CorsConfiguration.java

@@ -65,18 +65,25 @@ public class CorsConfiguration {
 	}
 
 
+	@Nullable
 	private List<String> allowedOrigins;
 
+	@Nullable
 	private List<String> allowedMethods;
 
+	@Nullable
 	private List<HttpMethod> resolvedMethods = DEFAULT_METHODS;
 
+	@Nullable
 	private List<String> allowedHeaders;
 
+	@Nullable
 	private List<String> exposedHeaders;
 
+	@Nullable
 	private Boolean allowCredentials;
 
+	@Nullable
 	private Long maxAge;
 
 

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

@@ -17,7 +17,6 @@
 package org.springframework.web.filter;
 
 import java.io.IOException;
-
 import javax.servlet.Filter;
 import javax.servlet.FilterChain;
 import javax.servlet.ServletException;
@@ -82,14 +81,18 @@ import org.springframework.web.context.support.WebApplicationContextUtils;
  */
 public class DelegatingFilterProxy extends GenericFilterBean {
 
+	@Nullable
 	private String contextAttribute;
 
+	@Nullable
 	private WebApplicationContext webApplicationContext;
 
+	@Nullable
 	private String targetBeanName;
 
 	private boolean targetFilterLifecycle = false;
 
+	@Nullable
 	private volatile Filter delegate;
 
 	private final Object delegateMonitor = new Object();
@@ -117,7 +120,7 @@ public class DelegatingFilterProxy extends GenericFilterBean {
 	 * @see #setEnvironment(org.springframework.core.env.Environment)
 	 */
 	public DelegatingFilterProxy(Filter delegate) {
-		Assert.notNull(delegate, "delegate Filter object must not be null");
+		Assert.notNull(delegate, "Delegate Filter must not be null");
 		this.delegate = delegate;
 	}
 
@@ -197,6 +200,7 @@ public class DelegatingFilterProxy extends GenericFilterBean {
 	/**
 	 * Return the name of the target bean in the Spring application context.
 	 */
+	@Nullable
 	protected String getTargetBeanName() {
 		return this.targetBeanName;
 	}
@@ -249,15 +253,16 @@ public class DelegatingFilterProxy extends GenericFilterBean {
 		Filter delegateToUse = this.delegate;
 		if (delegateToUse == null) {
 			synchronized (this.delegateMonitor) {
-				if (this.delegate == null) {
+				delegateToUse = this.delegate;
+				if (delegateToUse == null) {
 					WebApplicationContext wac = findWebApplicationContext();
 					if (wac == null) {
 						throw new IllegalStateException("No WebApplicationContext found: " +
 								"no ContextLoaderListener or DispatcherServlet registered?");
 					}
-					this.delegate = initDelegate(wac);
+					delegateToUse = initDelegate(wac);
 				}
-				delegateToUse = this.delegate;
+				this.delegate = delegateToUse;
 			}
 		}
 
@@ -327,7 +332,9 @@ public class DelegatingFilterProxy extends GenericFilterBean {
 	 * @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
 	 */
 	protected Filter initDelegate(WebApplicationContext wac) throws ServletException {
-		Filter delegate = wac.getBean(getTargetBeanName(), Filter.class);
+		String targetBeanName = getTargetBeanName();
+		Assert.state(targetBeanName != null, "No target bean name set");
+		Filter delegate = wac.getBean(targetBeanName, Filter.class);
 		if (isTargetFilterLifecycle()) {
 			delegate.init(getFilterConfig());
 		}

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

@@ -187,10 +187,12 @@ public class ForwardedHeaderFilter extends OncePerRequestFilter {
 	 */
 	private static class ForwardedHeaderExtractingRequest extends ForwardedHeaderRemovingRequest {
 
+		@Nullable
 		private final String scheme;
 
 		private final boolean secure;
 
+		@Nullable
 		private final String host;
 
 		private final int port;
@@ -238,11 +240,13 @@ public class ForwardedHeaderFilter extends OncePerRequestFilter {
 		}
 
 		@Override
+		@Nullable
 		public String getScheme() {
 			return this.scheme;
 		}
 
 		@Override
+		@Nullable
 		public String getServerName() {
 			return this.host;
 		}

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

@@ -84,12 +84,16 @@ public abstract class GenericFilterBean implements Filter, BeanNameAware, Enviro
 	/** Logger available to subclasses */
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private String beanName;
 
+	@Nullable
 	private Environment environment;
 
+	@Nullable
 	private ServletContext servletContext;
 
+	@Nullable
 	private FilterConfig filterConfig;
 
 	private final Set<String> requiredProperties = new HashSet<>(4);

spring-web/src/main/java/org/springframework/web/method/ControllerAdviceBean.java

@@ -54,6 +54,7 @@ public class ControllerAdviceBean implements Ordered {
 
 	private final Object bean;
 
+	@Nullable
 	private final BeanFactory beanFactory;
 
 	private final int order;
@@ -137,7 +138,7 @@ public class ControllerAdviceBean implements Ordered {
 	@Nullable
 	public Class<?> getBeanType() {
 		Class<?> beanType = (this.bean instanceof String ?
-				this.beanFactory.getType((String) this.bean) : this.bean.getClass());
+				obtainBeanFactory().getType((String) this.bean) : this.bean.getClass());
 		return (beanType != null ? ClassUtils.getUserClass(beanType) : null);
 	}
 
@@ -145,7 +146,12 @@ public class ControllerAdviceBean implements Ordered {
 	 * Return a bean instance if necessary resolving the bean name through the BeanFactory.
 	 */
 	public Object resolveBean() {
-		return (this.bean instanceof String ? this.beanFactory.getBean((String) this.bean) : this.bean);
+		return (this.bean instanceof String ? obtainBeanFactory().getBean((String) this.bean) : this.bean);
+	}
+
+	private BeanFactory obtainBeanFactory() {
+		Assert.state(this.beanFactory != null, "No BeanFactory set");
+		return this.beanFactory;
 	}
 
 	/**

spring-web/src/main/java/org/springframework/web/method/HandlerMethod.java

@@ -58,6 +58,7 @@ public class HandlerMethod {
 
 	private final Object bean;
 
+	@Nullable
 	private final BeanFactory beanFactory;
 
 	private final Class<?> beanType;
@@ -118,7 +119,10 @@ public class HandlerMethod {
 		this.bean = beanName;
 		this.beanFactory = beanFactory;
 		Class<?> beanType = beanFactory.getType(beanName);
-		this.beanType = (beanType != null ? ClassUtils.getUserClass(beanType) : null);
+		if (beanType == null) {
+			throw new IllegalStateException("Cannot resolve bean type for bean with name '" + beanName + "'");
+		}
+		this.beanType = ClassUtils.getUserClass(beanType);
 		this.method = method;
 		this.bridgedMethod = BridgeMethodResolver.findBridgedMethod(method);
 		this.parameters = initMethodParameters();
@@ -301,6 +305,7 @@ public class HandlerMethod {
 	public HandlerMethod createWithResolvedBean() {
 		Object handler = this.bean;
 		if (this.bean instanceof String) {
+			Assert.state(this.beanFactory != null, "Cannot resolve bean name without BeanFactory");
 			String beanName = (String) this.bean;
 			handler = this.beanFactory.getBean(beanName);
 		}
@@ -380,6 +385,7 @@ public class HandlerMethod {
 	 */
 	private class ReturnValueMethodParameter extends HandlerMethodParameter {
 
+		@Nullable
 		private final Object returnValue;
 
 		public ReturnValueMethodParameter(@Nullable Object returnValue) {

spring-web/src/main/java/org/springframework/web/method/annotation/AbstractNamedValueMethodArgumentResolver.java

@@ -63,8 +63,10 @@ import org.springframework.web.method.support.ModelAndViewContainer;
  */
 public abstract class AbstractNamedValueMethodArgumentResolver implements HandlerMethodArgumentResolver {
 
+	@Nullable
 	private final ConfigurableBeanFactory configurableBeanFactory;
 
+	@Nullable
 	private final BeanExpressionContext expressionContext;
 
 	private final Map<MethodParameter, NamedValueInfo> namedValueInfoCache = new ConcurrentHashMap<>(256);
@@ -268,6 +270,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 
 		private final boolean required;
 
+		@Nullable
 		private final String defaultValue;
 
 		public NamedValueInfo(String name, boolean required, @Nullable String defaultValue) {

spring-web/src/main/java/org/springframework/web/method/annotation/ExceptionHandlerMethodResolver.java

@@ -22,14 +22,13 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
 
 import org.springframework.core.ExceptionDepthComparator;
 import org.springframework.core.MethodIntrospector;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
-import org.springframework.util.ClassUtils;
+import org.springframework.util.ConcurrentReferenceHashMap;
 import org.springframework.util.ReflectionUtils.MethodFilter;
 import org.springframework.web.bind.annotation.ExceptionHandler;
 
@@ -50,17 +49,10 @@ public class ExceptionHandlerMethodResolver {
 	public static final MethodFilter EXCEPTION_HANDLER_METHODS = method ->
 			(AnnotationUtils.findAnnotation(method, ExceptionHandler.class) != null);
 
-	/**
-	 * Arbitrary {@link Method} reference, indicating no method found in the cache.
-	 */
-	private static final Method NO_METHOD_FOUND = ClassUtils.getMethodIfAvailable(System.class, "currentTimeMillis");
 
+	private final Map<Class<? extends Throwable>, Method> mappedMethods = new ConcurrentReferenceHashMap<>(16);
 
-	private final Map<Class<? extends Throwable>, Method> mappedMethods =
-			new ConcurrentHashMap<>(16);
-
-	private final Map<Class<? extends Throwable>, Method> exceptionLookupCache =
-			new ConcurrentHashMap<>(16);
+	private final Map<Class<? extends Throwable>, Method> exceptionLookupCache = new ConcurrentReferenceHashMap<>(16);
 
 
 	/**
@@ -157,9 +149,9 @@ public class ExceptionHandlerMethodResolver {
 		Method method = this.exceptionLookupCache.get(exceptionType);
 		if (method == null) {
 			method = getMappedMethod(exceptionType);
-			this.exceptionLookupCache.put(exceptionType, (method != null ? method : NO_METHOD_FOUND));
+			this.exceptionLookupCache.put(exceptionType, method);
 		}
-		return (method != NO_METHOD_FOUND ? method : null);
+		return method;
 	}
 
 	/**