diff --git a/spring-test/src/main/java/org/springframework/mock/web/MockHttpServletRequest.java b/spring-test/src/main/java/org/springframework/mock/web/MockHttpServletRequest.java
index 83bb95ca0e..dc161f0daa 100644
--- a/spring-test/src/main/java/org/springframework/mock/web/MockHttpServletRequest.java
+++ b/spring-test/src/main/java/org/springframework/mock/web/MockHttpServletRequest.java
@@ -987,9 +987,9 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	}
 
 	/**
-	 * Add a header entry for the given name.
-	 * <p>While this method can take any {@code Object} as a parameter, it
-	 * is recommended to use the following types:
+	 * Add an HTTP header entry for the given name.
+	 * <p>While this method can take any {@code Object} as a parameter,
+	 * it is recommended to use the following types:
 	 * <ul>
 	 * <li>String or any Object to be converted using {@code toString()}; see {@link #getHeader}.</li>
 	 * <li>String, Number, or Date for date headers; see {@link #getDateHeader}.</li>
@@ -1041,6 +1041,15 @@ public class MockHttpServletRequest implements HttpServletRequest {
 		}
 	}
 
+	/**
+	 * Remove already registered values for the specified HTTP header, if any.
+	 * @since 5.1.1
+	 */
+	public void removeHeader(String name) {
+		Assert.notNull(name, "Header name must not be null");
+		this.headers.remove(name);
+	}
+
 	/**
 	 * Return the long timestamp for the date header with the given {@code name}.
 	 * <p>If the internal value representation is a String, this method will try
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/HeaderValueHolder.java b/spring-web/src/test/java/org/springframework/mock/web/test/HeaderValueHolder.java
index 6588a633e5..c5cf43172a 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/HeaderValueHolder.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/HeaderValueHolder.java
@@ -23,6 +23,7 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 
@@ -38,7 +39,7 @@ class HeaderValueHolder {
 	private final List<Object> values = new LinkedList<>();
 
 
-	public void setValue(Object value) {
+	public void setValue(@Nullable Object value) {
 		this.values.clear();
 		if (value != null) {
 			this.values.add(value);
@@ -69,10 +70,12 @@ class HeaderValueHolder {
 		return Collections.unmodifiableList(stringList);
 	}
 
+	@Nullable
 	public Object getValue() {
 		return (!this.values.isEmpty() ? this.values.get(0) : null);
 	}
 
+	@Nullable
 	public String getStringValue() {
 		return (!this.values.isEmpty() ? String.valueOf(this.values.get(0)) : null);
 	}
@@ -90,6 +93,7 @@ class HeaderValueHolder {
 	 * @return the corresponding HeaderValueHolder,
 	 * or {@code null} if none found
 	 */
+	@Nullable
 	public static HeaderValueHolder getByName(Map<String, HeaderValueHolder> headers, String name) {
 		Assert.notNull(name, "Header name must not be null");
 		for (String headerName : headers.keySet()) {
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockAsyncContext.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockAsyncContext.java
index 33f97100a7..ebe752cd22 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockAsyncContext.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockAsyncContext.java
@@ -116,7 +116,7 @@ public class MockAsyncContext implements AsyncContext {
 
 	@Override
 	public void complete() {
-		MockHttpServletRequest mockRequest = WebUtils.getNativeRequest(request, MockHttpServletRequest.class);
+		MockHttpServletRequest mockRequest = WebUtils.getNativeRequest(this.request, MockHttpServletRequest.class);
 		if (mockRequest != null) {
 			mockRequest.setAsyncStarted(false);
 		}
@@ -154,6 +154,17 @@ public class MockAsyncContext implements AsyncContext {
 		return BeanUtils.instantiateClass(clazz);
 	}
 
+	/**
+	 * By default this is set to 10000 (10 seconds) even though the Servlet API
+	 * specifies a default async request timeout of 30 seconds. Keep in mind the
+	 * timeout could further be impacted by global configuration through the MVC
+	 * Java config or the XML namespace, as well as be overridden per request on
+	 * {@link org.springframework.web.context.request.async.DeferredResult DeferredResult}
+	 * or on
+	 * {@link org.springframework.web.servlet.mvc.method.annotation.SseEmitter SseEmitter}.
+	 * @param timeout the timeout value to use.
+	 * @see AsyncContext#setTimeout(long)
+	 */
 	@Override
 	public void setTimeout(long timeout) {
 		this.timeout = timeout;
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockBodyContent.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockBodyContent.java
index 0c13774c0a..d02bb4c145 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockBodyContent.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockBodyContent.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 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 +24,8 @@ import javax.servlet.http.HttpServletResponse;
 import javax.servlet.jsp.JspWriter;
 import javax.servlet.jsp.tagext.BodyContent;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Mock implementation of the {@link javax.servlet.jsp.tagext.BodyContent} class.
  * Only necessary for testing applications when testing custom JSP tags.
@@ -60,12 +62,12 @@ public class MockBodyContent extends BodyContent {
 	 * @param response the servlet response to wrap
 	 * @param targetWriter the target Writer to wrap
 	 */
-	public MockBodyContent(String content, HttpServletResponse response, Writer targetWriter) {
+	public MockBodyContent(String content, @Nullable HttpServletResponse response, @Nullable Writer targetWriter) {
 		super(adaptJspWriter(targetWriter, response));
 		this.content = content;
 	}
 
-	private static JspWriter adaptJspWriter(Writer targetWriter, HttpServletResponse response) {
+	private static JspWriter adaptJspWriter(@Nullable Writer targetWriter, @Nullable HttpServletResponse response) {
 		if (targetWriter instanceof JspWriter) {
 			return (JspWriter) targetWriter;
 		}
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockFilterChain.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockFilterChain.java
index 7136d2160d..037465c90a 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockFilterChain.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockFilterChain.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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 javax.servlet.ServletException;
 import javax.servlet.ServletRequest;
 import javax.servlet.ServletResponse;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 
@@ -49,12 +50,15 @@ import org.springframework.util.ObjectUtils;
  */
 public class MockFilterChain implements FilterChain {
 
+	@Nullable
 	private ServletRequest request;
 
+	@Nullable
 	private ServletResponse response;
 
 	private final List<Filter> filters;
 
+	@Nullable
 	private Iterator<Filter> iterator;
 
 
@@ -97,6 +101,7 @@ public class MockFilterChain implements FilterChain {
 	/**
 	 * Return the request that {@link #doFilter} has been called with.
 	 */
+	@Nullable
 	public ServletRequest getRequest() {
 		return this.request;
 	}
@@ -104,12 +109,13 @@ public class MockFilterChain implements FilterChain {
 	/**
 	 * Return the response that {@link #doFilter} has been called with.
 	 */
+	@Nullable
 	public ServletResponse getResponse() {
 		return this.response;
 	}
 
 	/**
-	 * Invoke registered {@link Filter}s and/or {@link Servlet} also saving the
+	 * Invoke registered {@link Filter Filters} and/or {@link Servlet} also saving the
 	 * request and response.
 	 */
 	@Override
@@ -144,7 +150,7 @@ public class MockFilterChain implements FilterChain {
 	/**
 	 * A filter that simply delegates to a Servlet.
 	 */
-	private static class ServletFilterProxy implements Filter {
+	private static final class ServletFilterProxy implements Filter {
 
 		private final Servlet delegateServlet;
 
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockFilterConfig.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockFilterConfig.java
index fbfc1a17f3..01a1979cc7 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockFilterConfig.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockFilterConfig.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -23,6 +23,7 @@ import java.util.Map;
 import javax.servlet.FilterConfig;
 import javax.servlet.ServletContext;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -64,7 +65,7 @@ public class MockFilterConfig implements FilterConfig {
 	 * Create a new MockFilterConfig.
 	 * @param servletContext the ServletContext that the servlet runs in
 	 */
-	public MockFilterConfig(ServletContext servletContext) {
+	public MockFilterConfig(@Nullable ServletContext servletContext) {
 		this(servletContext, "");
 	}
 
@@ -73,7 +74,7 @@ public class MockFilterConfig implements FilterConfig {
 	 * @param servletContext the ServletContext that the servlet runs in
 	 * @param filterName the name of the filter
 	 */
-	public MockFilterConfig(ServletContext servletContext, String filterName) {
+	public MockFilterConfig(@Nullable ServletContext servletContext, String filterName) {
 		this.servletContext = (servletContext != null ? servletContext : new MockServletContext());
 		this.filterName = filterName;
 	}
@@ -81,12 +82,12 @@ public class MockFilterConfig implements FilterConfig {
 
 	@Override
 	public String getFilterName() {
-		return filterName;
+		return this.filterName;
 	}
 
 	@Override
 	public ServletContext getServletContext() {
-		return servletContext;
+		return this.servletContext;
 	}
 
 	public void addInitParameter(String name, String value) {
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockHttpServletRequest.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockHttpServletRequest.java
index 357239d1ed..d09c869745 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockHttpServletRequest.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockHttpServletRequest.java
@@ -58,6 +58,7 @@ import javax.servlet.http.Part;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.LinkedCaseInsensitiveMap;
 import org.springframework.util.LinkedMultiValueMap;
@@ -101,7 +102,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 			new BufferedReader(new StringReader(""));
 
 	/**
-	 * Date formats as specified in the HTTP RFC
+	 * Date formats as specified in the HTTP RFC.
 	 * @see <a href="https://tools.ietf.org/html/rfc7231#section-7.1.1.1">Section 7.1.1.1 of RFC 7231</a>
 	 */
 	private static final String[] DATE_FORMATS = new String[] {
@@ -168,14 +169,19 @@ public class MockHttpServletRequest implements HttpServletRequest {
 
 	private final Map<String, Object> attributes = new LinkedHashMap<>();
 
+	@Nullable
 	private String characterEncoding;
 
+	@Nullable
 	private byte[] content;
 
+	@Nullable
 	private String contentType;
 
+	@Nullable
 	private ServletInputStream inputStream;
 
+	@Nullable
 	private BufferedReader reader;
 
 	private final Map<String, String[]> parameters = new LinkedHashMap<>(16);
@@ -192,7 +198,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 
 	private String remoteHost = DEFAULT_REMOTE_HOST;
 
-	/** List of locales in descending order */
+	/** List of locales in descending order. */
 	private final List<Locale> locales = new LinkedList<>();
 
 	private boolean secure = false;
@@ -209,6 +215,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 
 	private boolean asyncSupported = false;
 
+	@Nullable
 	private MockAsyncContext asyncContext;
 
 	private DispatcherType dispatcherType = DispatcherType.REQUEST;
@@ -218,32 +225,42 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	// HttpServletRequest properties
 	// ---------------------------------------------------------------------
 
+	@Nullable
 	private String authType;
 
+	@Nullable
 	private Cookie[] cookies;
 
 	private final Map<String, HeaderValueHolder> headers = new LinkedCaseInsensitiveMap<>();
 
+	@Nullable
 	private String method;
 
+	@Nullable
 	private String pathInfo;
 
 	private String contextPath = "";
 
+	@Nullable
 	private String queryString;
 
+	@Nullable
 	private String remoteUser;
 
 	private final Set<String> userRoles = new HashSet<>();
 
+	@Nullable
 	private Principal userPrincipal;
 
+	@Nullable
 	private String requestedSessionId;
 
+	@Nullable
 	private String requestURI;
 
 	private String servletPath = "";
 
+	@Nullable
 	private HttpSession session;
 
 	private boolean requestedSessionIdValid = true;
@@ -277,7 +294,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	 * @see #setRequestURI
 	 * @see #MockHttpServletRequest(ServletContext, String, String)
 	 */
-	public MockHttpServletRequest(String method, String requestURI) {
+	public MockHttpServletRequest(@Nullable String method, @Nullable String requestURI) {
 		this(null, method, requestURI);
 	}
 
@@ -287,7 +304,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	 * (may be {@code null} to use a default {@link MockServletContext})
 	 * @see #MockHttpServletRequest(ServletContext, String, String)
 	 */
-	public MockHttpServletRequest(ServletContext servletContext) {
+	public MockHttpServletRequest(@Nullable ServletContext servletContext) {
 		this(servletContext, "", "");
 	}
 
@@ -304,7 +321,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	 * @see #setPreferredLocales
 	 * @see MockServletContext
 	 */
-	public MockHttpServletRequest(ServletContext servletContext, String method, String requestURI) {
+	public MockHttpServletRequest(@Nullable ServletContext servletContext, @Nullable String method, @Nullable String requestURI) {
 		this.servletContext = (servletContext != null ? servletContext : new MockServletContext());
 		this.method = method;
 		this.requestURI = requestURI;
@@ -373,12 +390,13 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	}
 
 	@Override
+	@Nullable
 	public String getCharacterEncoding() {
 		return this.characterEncoding;
 	}
 
 	@Override
-	public void setCharacterEncoding(String characterEncoding) {
+	public void setCharacterEncoding(@Nullable String characterEncoding) {
 		this.characterEncoding = characterEncoding;
 		updateContentTypeHeader();
 	}
@@ -403,7 +421,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	 * @see #getContentAsByteArray()
 	 * @see #getContentAsString()
 	 */
-	public void setContent(byte[] content) {
+	public void setContent(@Nullable byte[] content) {
 		this.content = content;
 	}
 
@@ -414,6 +432,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	 * @see #setContent(byte[])
 	 * @see #getContentAsString()
 	 */
+	@Nullable
 	public byte[] getContentAsByteArray() {
 		return this.content;
 	}
@@ -429,6 +448,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	 * @see #setCharacterEncoding(String)
 	 * @see #getContentAsByteArray()
 	 */
+	@Nullable
 	public String getContentAsString() throws IllegalStateException, UnsupportedEncodingException {
 		Assert.state(this.characterEncoding != null,
 				"Cannot get content as a String for a null character encoding. " +
@@ -450,7 +470,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 		return getContentLength();
 	}
 
-	public void setContentType(String contentType) {
+	public void setContentType(@Nullable String contentType) {
 		this.contentType = contentType;
 		if (contentType != null) {
 			try {
@@ -471,6 +491,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	}
 
 	@Override
+	@Nullable
 	public String getContentType() {
 		return this.contentType;
 	}
@@ -536,7 +557,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	 * <p>If there are already one or more values registered for the given
 	 * parameter name, the given value will be added to the end of the list.
 	 */
-	public void addParameter(String name, String value) {
+	public void addParameter(String name, @Nullable String value) {
 		addParameter(name, new String[] {value});
 	}
 
@@ -596,6 +617,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	}
 
 	@Override
+	@Nullable
 	public String getParameter(String name) {
 		Assert.notNull(name, "Parameter name must not be null");
 		String[] arr = this.parameters.get(name);
@@ -725,7 +747,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	}
 
 	@Override
-	public void setAttribute(String name, Object value) {
+	public void setAttribute(String name, @Nullable Object value) {
 		checkActive();
 		Assert.notNull(name, "Attribute name must not be null");
 		if (value != null) {
@@ -763,8 +785,8 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	/**
 	 * Set the list of preferred locales, in descending order, effectively replacing
 	 * any existing locales.
-	 * @see #addPreferredLocale
 	 * @since 3.2
+	 * @see #addPreferredLocale
 	 */
 	public void setPreferredLocales(List<Locale> locales) {
 		Assert.notEmpty(locales, "Locale list must not be empty");
@@ -889,7 +911,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	}
 
 	@Override
-	public AsyncContext startAsync(ServletRequest request, ServletResponse response) {
+	public AsyncContext startAsync(ServletRequest request, @Nullable ServletResponse response) {
 		Assert.state(this.asyncSupported, "Async not supported");
 		this.asyncStarted = true;
 		this.asyncContext = new MockAsyncContext(request, response);
@@ -914,11 +936,12 @@ public class MockHttpServletRequest implements HttpServletRequest {
 		return this.asyncSupported;
 	}
 
-	public void setAsyncContext(MockAsyncContext asyncContext) {
+	public void setAsyncContext(@Nullable MockAsyncContext asyncContext) {
 		this.asyncContext = asyncContext;
 	}
 
 	@Override
+	@Nullable
 	public AsyncContext getAsyncContext() {
 		return this.asyncContext;
 	}
@@ -937,16 +960,17 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	// HttpServletRequest interface
 	// ---------------------------------------------------------------------
 
-	public void setAuthType(String authType) {
+	public void setAuthType(@Nullable String authType) {
 		this.authType = authType;
 	}
 
 	@Override
+	@Nullable
 	public String getAuthType() {
 		return this.authType;
 	}
 
-	public void setCookies(Cookie... cookies) {
+	public void setCookies(@Nullable Cookie... cookies) {
 		this.cookies = (ObjectUtils.isEmpty(cookies) ? null : cookies);
 		this.headers.remove(HttpHeaders.COOKIE);
 		if (this.cookies != null) {
@@ -957,14 +981,15 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	}
 
 	@Override
+	@Nullable
 	public Cookie[] getCookies() {
 		return this.cookies;
 	}
 
 	/**
-	 * Add a header entry for the given name.
-	 * <p>While this method can take any {@code Object} as a parameter, it
-	 * is recommended to use the following types:
+	 * Add an HTTP header entry for the given name.
+	 * <p>While this method can take any {@code Object} as a parameter,
+	 * it is recommended to use the following types:
 	 * <ul>
 	 * <li>String or any Object to be converted using {@code toString()}; see {@link #getHeader}.</li>
 	 * <li>String, Number, or Date for date headers; see {@link #getDateHeader}.</li>
@@ -998,7 +1023,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 		}
 	}
 
-	private void doAddHeaderValue(String name, Object value, boolean replace) {
+	private void doAddHeaderValue(String name, @Nullable Object value, boolean replace) {
 		HeaderValueHolder header = HeaderValueHolder.getByName(this.headers, name);
 		Assert.notNull(value, "Header value must not be null");
 		if (header == null || replace) {
@@ -1016,6 +1041,15 @@ public class MockHttpServletRequest implements HttpServletRequest {
 		}
 	}
 
+	/**
+	 * Remove already registered values for the specified HTTP header, if any.
+	 * @since 5.1.1
+	 */
+	public void removeHeader(String name) {
+		Assert.notNull(name, "Header name must not be null");
+		this.headers.remove(name);
+	}
+
 	/**
 	 * Return the long timestamp for the date header with the given {@code name}.
 	 * <p>If the internal value representation is a String, this method will try
@@ -1065,6 +1099,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	}
 
 	@Override
+	@Nullable
 	public String getHeader(String name) {
 		HeaderValueHolder header = HeaderValueHolder.getByName(this.headers, name);
 		return (header != null ? header.getStringValue() : null);
@@ -1099,25 +1134,28 @@ public class MockHttpServletRequest implements HttpServletRequest {
 		}
 	}
 
-	public void setMethod(String method) {
+	public void setMethod(@Nullable String method) {
 		this.method = method;
 	}
 
 	@Override
+	@Nullable
 	public String getMethod() {
 		return this.method;
 	}
 
-	public void setPathInfo(String pathInfo) {
+	public void setPathInfo(@Nullable String pathInfo) {
 		this.pathInfo = pathInfo;
 	}
 
 	@Override
+	@Nullable
 	public String getPathInfo() {
 		return this.pathInfo;
 	}
 
 	@Override
+	@Nullable
 	public String getPathTranslated() {
 		return (this.pathInfo != null ? getRealPath(this.pathInfo) : null);
 	}
@@ -1131,20 +1169,22 @@ public class MockHttpServletRequest implements HttpServletRequest {
 		return this.contextPath;
 	}
 
-	public void setQueryString(String queryString) {
+	public void setQueryString(@Nullable String queryString) {
 		this.queryString = queryString;
 	}
 
 	@Override
+	@Nullable
 	public String getQueryString() {
 		return this.queryString;
 	}
 
-	public void setRemoteUser(String remoteUser) {
+	public void setRemoteUser(@Nullable String remoteUser) {
 		this.remoteUser = remoteUser;
 	}
 
 	@Override
+	@Nullable
 	public String getRemoteUser() {
 		return this.remoteUser;
 	}
@@ -1159,29 +1199,32 @@ public class MockHttpServletRequest implements HttpServletRequest {
 				((MockServletContext) this.servletContext).getDeclaredRoles().contains(role)));
 	}
 
-	public void setUserPrincipal(Principal userPrincipal) {
+	public void setUserPrincipal(@Nullable Principal userPrincipal) {
 		this.userPrincipal = userPrincipal;
 	}
 
 	@Override
+	@Nullable
 	public Principal getUserPrincipal() {
 		return this.userPrincipal;
 	}
 
-	public void setRequestedSessionId(String requestedSessionId) {
+	public void setRequestedSessionId(@Nullable String requestedSessionId) {
 		this.requestedSessionId = requestedSessionId;
 	}
 
 	@Override
+	@Nullable
 	public String getRequestedSessionId() {
 		return this.requestedSessionId;
 	}
 
-	public void setRequestURI(String requestURI) {
+	public void setRequestURI(@Nullable String requestURI) {
 		this.requestURI = requestURI;
 	}
 
 	@Override
+	@Nullable
 	public String getRequestURI() {
 		return this.requestURI;
 	}
@@ -1222,6 +1265,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	}
 
 	@Override
+	@Nullable
 	public HttpSession getSession(boolean create) {
 		checkActive();
 		// Reset session if invalidated.
@@ -1236,6 +1280,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	}
 
 	@Override
+	@Nullable
 	public HttpSession getSession() {
 		return getSession(true);
 	}
@@ -1249,7 +1294,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	public String changeSessionId() {
 		Assert.isTrue(this.session != null, "The request does not have a session");
 		if (this.session instanceof MockHttpSession) {
-			return ((MockHttpSession) session).changeSessionId();
+			return ((MockHttpSession) this.session).changeSessionId();
 		}
 		return this.session.getId();
 	}
@@ -1309,6 +1354,7 @@ public class MockHttpServletRequest implements HttpServletRequest {
 	}
 
 	@Override
+	@Nullable
 	public Part getPart(String name) throws IOException, ServletException {
 		return this.parts.getFirst(name);
 	}
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockHttpSession.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockHttpSession.java
index 03d4e2cf5a..1013b6b507 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockHttpSession.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockHttpSession.java
@@ -29,6 +29,7 @@ import javax.servlet.http.HttpSession;
 import javax.servlet.http.HttpSessionBindingEvent;
 import javax.servlet.http.HttpSessionBindingListener;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -84,7 +85,7 @@ public class MockHttpSession implements HttpSession {
 	 * Create a new MockHttpSession.
 	 * @param servletContext the ServletContext that the session runs in
 	 */
-	public MockHttpSession(ServletContext servletContext) {
+	public MockHttpSession(@Nullable ServletContext servletContext) {
 		this(servletContext, null);
 	}
 
@@ -93,7 +94,7 @@ public class MockHttpSession implements HttpSession {
 	 * @param servletContext the ServletContext that the session runs in
 	 * @param id a unique identifier for this session
 	 */
-	public MockHttpSession(ServletContext servletContext, String id) {
+	public MockHttpSession(@Nullable ServletContext servletContext, @Nullable String id) {
 		this.servletContext = (servletContext != null ? servletContext : new MockServletContext());
 		this.id = (id != null ? id : Integer.toString(nextId++));
 	}
@@ -176,7 +177,7 @@ public class MockHttpSession implements HttpSession {
 	}
 
 	@Override
-	public void setAttribute(String name, Object value) {
+	public void setAttribute(String name, @Nullable Object value) {
 		assertIsValid();
 		Assert.notNull(name, "Attribute name must not be null");
 		if (value != null) {
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockJspWriter.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockJspWriter.java
index 23df842dbf..e1447d0a35 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockJspWriter.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockJspWriter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 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 +22,8 @@ import java.io.Writer;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.jsp.JspWriter;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Mock implementation of the {@link javax.servlet.jsp.JspWriter} class.
  * Only necessary for testing applications when testing custom JSP tags.
@@ -33,6 +35,7 @@ public class MockJspWriter extends JspWriter {
 
 	private final HttpServletResponse response;
 
+	@Nullable
 	private PrintWriter targetWriter;
 
 
@@ -58,7 +61,7 @@ public class MockJspWriter extends JspWriter {
 	 * @param response the servlet response to wrap
 	 * @param targetWriter the target Writer to wrap
 	 */
-	public MockJspWriter(HttpServletResponse response, Writer targetWriter) {
+	public MockJspWriter(@Nullable HttpServletResponse response, @Nullable Writer targetWriter) {
 		super(DEFAULT_BUFFER, true);
 		this.response = (response != null ? response : new MockHttpServletResponse());
 		if (targetWriter instanceof PrintWriter) {
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockMultipartFile.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockMultipartFile.java
index 29193640f5..62cf0e9391 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockMultipartFile.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockMultipartFile.java
@@ -21,6 +21,7 @@ import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.FileCopyUtils;
 import org.springframework.web.multipart.MultipartFile;
@@ -43,6 +44,7 @@ public class MockMultipartFile implements MultipartFile {
 
 	private String originalFilename;
 
+	@Nullable
 	private String contentType;
 
 	private final byte[] content;
@@ -53,7 +55,7 @@ public class MockMultipartFile implements MultipartFile {
 	 * @param name the name of the file
 	 * @param content the content of the file
 	 */
-	public MockMultipartFile(String name, byte[] content) {
+	public MockMultipartFile(String name, @Nullable byte[] content) {
 		this(name, "", null, content);
 	}
 
@@ -74,7 +76,9 @@ public class MockMultipartFile implements MultipartFile {
 	 * @param contentType the content type (if known)
 	 * @param content the content of the file
 	 */
-	public MockMultipartFile(String name, String originalFilename, String contentType, byte[] content) {
+	public MockMultipartFile(
+			String name, @Nullable String originalFilename, @Nullable String contentType, @Nullable byte[] content) {
+
 		Assert.hasLength(name, "Name must not be null");
 		this.name = name;
 		this.originalFilename = (originalFilename != null ? originalFilename : "");
@@ -90,7 +94,8 @@ public class MockMultipartFile implements MultipartFile {
 	 * @param contentStream the content of the file as stream
 	 * @throws IOException if reading from the stream failed
 	 */
-	public MockMultipartFile(String name, String originalFilename, String contentType, InputStream contentStream)
+	public MockMultipartFile(
+			String name, @Nullable String originalFilename, @Nullable String contentType, InputStream contentStream)
 			throws IOException {
 
 		this(name, originalFilename, contentType, FileCopyUtils.copyToByteArray(contentStream));
@@ -108,6 +113,7 @@ public class MockMultipartFile implements MultipartFile {
 	}
 
 	@Override
+	@Nullable
 	public String getContentType() {
 		return this.contentType;
 	}
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockMultipartHttpServletRequest.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockMultipartHttpServletRequest.java
index d74c24c077..3f6ca2c55e 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockMultipartHttpServletRequest.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockMultipartHttpServletRequest.java
@@ -25,6 +25,7 @@ import javax.servlet.ServletContext;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
@@ -65,7 +66,7 @@ public class MockMultipartHttpServletRequest extends MockHttpServletRequest impl
 	 * @param servletContext the ServletContext that the request runs in
 	 * (may be {@code null} to use a default {@link MockServletContext})
 	 */
-	public MockMultipartHttpServletRequest(ServletContext servletContext) {
+	public MockMultipartHttpServletRequest(@Nullable ServletContext servletContext) {
 		super(servletContext);
 		setMethod("POST");
 		setContentType("multipart/form-data");
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockPageContext.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockPageContext.java
index 16cc0f3413..8812a51e47 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockPageContext.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockPageContext.java
@@ -36,6 +36,7 @@ import javax.servlet.http.HttpSession;
 import javax.servlet.jsp.JspWriter;
 import javax.servlet.jsp.PageContext;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -61,6 +62,7 @@ public class MockPageContext extends PageContext {
 
 	private final Map<String, Object> attributes = new LinkedHashMap<>();
 
+	@Nullable
 	private JspWriter out;
 
 
@@ -79,7 +81,7 @@ public class MockPageContext extends PageContext {
 	 * @param servletContext the ServletContext that the JSP page runs in
 	 * (only necessary when actually accessing the ServletContext)
 	 */
-	public MockPageContext(ServletContext servletContext) {
+	public MockPageContext(@Nullable ServletContext servletContext) {
 		this(servletContext, null, null, null);
 	}
 
@@ -90,7 +92,7 @@ public class MockPageContext extends PageContext {
 	 * @param request the current HttpServletRequest
 	 * (only necessary when actually accessing the request)
 	 */
-	public MockPageContext(ServletContext servletContext, HttpServletRequest request) {
+	public MockPageContext(@Nullable ServletContext servletContext, @Nullable HttpServletRequest request) {
 		this(servletContext, request, null, null);
 	}
 
@@ -101,7 +103,9 @@ public class MockPageContext extends PageContext {
 	 * @param response the current HttpServletResponse
 	 * (only necessary when actually writing to the response)
 	 */
-	public MockPageContext(ServletContext servletContext, HttpServletRequest request, HttpServletResponse response) {
+	public MockPageContext(@Nullable ServletContext servletContext, @Nullable HttpServletRequest request,
+			@Nullable HttpServletResponse response) {
+
 		this(servletContext, request, response, null);
 	}
 
@@ -112,8 +116,8 @@ public class MockPageContext extends PageContext {
 	 * @param response the current HttpServletResponse
 	 * @param servletConfig the ServletConfig (hardly ever accessed from within a tag)
 	 */
-	public MockPageContext(ServletContext servletContext, HttpServletRequest request,
-			HttpServletResponse response, ServletConfig servletConfig) {
+	public MockPageContext(@Nullable ServletContext servletContext, @Nullable HttpServletRequest request,
+			@Nullable HttpServletResponse response, @Nullable ServletConfig servletConfig) {
 
 		this.servletContext = (servletContext != null ? servletContext : new MockServletContext());
 		this.request = (request != null ? request : new MockHttpServletRequest(servletContext));
@@ -135,7 +139,7 @@ public class MockPageContext extends PageContext {
 	}
 
 	@Override
-	public void setAttribute(String name, Object value) {
+	public void setAttribute(String name, @Nullable Object value) {
 		Assert.notNull(name, "Attribute name must not be null");
 		if (value != null) {
 			this.attributes.put(name, value);
@@ -146,7 +150,7 @@ public class MockPageContext extends PageContext {
 	}
 
 	@Override
-	public void setAttribute(String name, Object value, int scope) {
+	public void setAttribute(String name, @Nullable Object value, int scope) {
 		Assert.notNull(name, "Attribute name must not be null");
 		switch (scope) {
 			case PAGE_SCOPE:
@@ -167,12 +171,14 @@ public class MockPageContext extends PageContext {
 	}
 
 	@Override
+	@Nullable
 	public Object getAttribute(String name) {
 		Assert.notNull(name, "Attribute name must not be null");
 		return this.attributes.get(name);
 	}
 
 	@Override
+	@Nullable
 	public Object getAttribute(String name, int scope) {
 		Assert.notNull(name, "Attribute name must not be null");
 		switch (scope) {
@@ -191,6 +197,7 @@ public class MockPageContext extends PageContext {
 	}
 
 	@Override
+	@Nullable
 	public Object findAttribute(String name) {
 		Object value = getAttribute(name);
 		if (value == null) {
@@ -290,12 +297,14 @@ public class MockPageContext extends PageContext {
 	}
 
 	@Override
+	@Nullable
 	public ELContext getELContext() {
 		return null;
 	}
 
 	@Override
 	@Deprecated
+	@Nullable
 	public javax.servlet.jsp.el.VariableResolver getVariableResolver() {
 		return null;
 	}
@@ -321,6 +330,7 @@ public class MockPageContext extends PageContext {
 	}
 
 	@Override
+	@Nullable
 	public Exception getException() {
 		return null;
 	}
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockPart.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockPart.java
index a5429b3847..8233baaa96 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockPart.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockPart.java
@@ -25,6 +25,7 @@ import javax.servlet.http.Part;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -40,6 +41,7 @@ public class MockPart implements Part {
 
 	private final String name;
 
+	@Nullable
 	private final String filename;
 
 	private final byte[] content;
@@ -51,7 +53,7 @@ public class MockPart implements Part {
 	 * Constructor for a part with byte[] content only.
 	 * @see #getHeaders()
 	 */
-	public MockPart(String name, byte[] content) {
+	public MockPart(String name, @Nullable byte[] content) {
 		this(name, null, content);
 	}
 
@@ -59,7 +61,7 @@ public class MockPart implements Part {
 	 * Constructor for a part with a filename and byte[] content.
 	 * @see #getHeaders()
 	 */
-	public MockPart(String name, String filename, byte[] content) {
+	public MockPart(String name, @Nullable String filename, @Nullable byte[] content) {
 		Assert.hasLength(name, "'name' must not be empty");
 		this.name = name;
 		this.filename = filename;
@@ -74,11 +76,13 @@ public class MockPart implements Part {
 	}
 
 	@Override
+	@Nullable
 	public String getSubmittedFileName() {
 		return this.filename;
 	}
 
 	@Override
+	@Nullable
 	public String getContentType() {
 		MediaType contentType = this.headers.getContentType();
 		return (contentType != null ? contentType.toString() : null);
@@ -105,6 +109,7 @@ public class MockPart implements Part {
 	}
 
 	@Override
+	@Nullable
 	public String getHeader(String name) {
 		return this.headers.getFirst(name);
 	}
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockServletConfig.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockServletConfig.java
index c73d05d657..a6d3cd87bc 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockServletConfig.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockServletConfig.java
@@ -23,6 +23,7 @@ import java.util.Map;
 import javax.servlet.ServletConfig;
 import javax.servlet.ServletContext;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -60,7 +61,7 @@ public class MockServletConfig implements ServletConfig {
 	 * Create a new MockServletConfig.
 	 * @param servletContext the ServletContext that the servlet runs in
 	 */
-	public MockServletConfig(ServletContext servletContext) {
+	public MockServletConfig(@Nullable ServletContext servletContext) {
 		this(servletContext, "");
 	}
 
@@ -69,7 +70,7 @@ public class MockServletConfig implements ServletConfig {
 	 * @param servletContext the ServletContext that the servlet runs in
 	 * @param servletName the name of the servlet
 	 */
-	public MockServletConfig(ServletContext servletContext, String servletName) {
+	public MockServletConfig(@Nullable ServletContext servletContext, String servletName) {
 		this.servletContext = (servletContext != null ? servletContext : new MockServletContext());
 		this.servletName = servletName;
 	}
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockServletContext.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockServletContext.java
index e66cb14266..11caa42471 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockServletContext.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockServletContext.java
@@ -48,6 +48,7 @@ import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.http.MediaType;
 import org.springframework.http.MediaTypeFactory;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.MimeType;
@@ -129,14 +130,17 @@ public class MockServletContext implements ServletContext {
 
 	private final Set<String> declaredRoles = new LinkedHashSet<>();
 
+	@Nullable
 	private Set<SessionTrackingMode> sessionTrackingModes;
 
 	private final SessionCookieConfig sessionCookieConfig = new MockSessionCookieConfig();
 
 	private int sessionTimeout;
 
+	@Nullable
 	private String requestCharacterEncoding;
 
+	@Nullable
 	private String responseCharacterEncoding;
 
 	private final Map<String, MediaType> mimeTypes = new LinkedHashMap<>();
@@ -165,7 +169,7 @@ public class MockServletContext implements ServletContext {
 	 * and no base path.
 	 * @param resourceLoader the ResourceLoader to use (or null for the default)
 	 */
-	public MockServletContext(ResourceLoader resourceLoader) {
+	public MockServletContext(@Nullable ResourceLoader resourceLoader) {
 		this("", resourceLoader);
 	}
 
@@ -178,7 +182,7 @@ public class MockServletContext implements ServletContext {
 	 * @param resourceLoader the ResourceLoader to use (or null for the default)
 	 * @see #registerNamedDispatcher
 	 */
-	public MockServletContext(String resourceBasePath, ResourceLoader resourceLoader) {
+	public MockServletContext(String resourceBasePath, @Nullable ResourceLoader resourceLoader) {
 		this.resourceLoader = (resourceLoader != null ? resourceLoader : new DefaultResourceLoader());
 		this.resourceBasePath = resourceBasePath;
 
@@ -262,6 +266,7 @@ public class MockServletContext implements ServletContext {
 	}
 
 	@Override
+	@Nullable
 	public String getMimeType(String filePath) {
 		String extension = StringUtils.getFilenameExtension(filePath);
 		if (this.mimeTypes.containsKey(extension)) {
@@ -285,6 +290,7 @@ public class MockServletContext implements ServletContext {
 	}
 
 	@Override
+	@Nullable
 	public Set<String> getResourcePaths(String path) {
 		String actualPath = (path.endsWith("/") ? path : path + "/");
 		Resource resource = this.resourceLoader.getResource(getResourceLocation(actualPath));
@@ -313,6 +319,7 @@ public class MockServletContext implements ServletContext {
 	}
 
 	@Override
+	@Nullable
 	public URL getResource(String path) throws MalformedURLException {
 		Resource resource = this.resourceLoader.getResource(getResourceLocation(path));
 		if (!resource.exists()) {
@@ -333,6 +340,7 @@ public class MockServletContext implements ServletContext {
 	}
 
 	@Override
+	@Nullable
 	public InputStream getResourceAsStream(String path) {
 		Resource resource = this.resourceLoader.getResource(getResourceLocation(path));
 		if (!resource.exists()) {
@@ -414,6 +422,7 @@ public class MockServletContext implements ServletContext {
 
 	@Deprecated
 	@Override
+	@Nullable
 	public Servlet getServlet(String name) {
 		return null;
 	}
@@ -447,6 +456,7 @@ public class MockServletContext implements ServletContext {
 	}
 
 	@Override
+	@Nullable
 	public String getRealPath(String path) {
 		Resource resource = this.resourceLoader.getResource(getResourceLocation(path));
 		try {
@@ -492,6 +502,7 @@ public class MockServletContext implements ServletContext {
 	}
 
 	@Override
+	@Nullable
 	public Object getAttribute(String name) {
 		Assert.notNull(name, "Attribute name must not be null");
 		return this.attributes.get(name);
@@ -503,7 +514,7 @@ public class MockServletContext implements ServletContext {
 	}
 
 	@Override
-	public void setAttribute(String name, Object value) {
+	public void setAttribute(String name, @Nullable Object value) {
 		Assert.notNull(name, "Attribute name must not be null");
 		if (value != null) {
 			this.attributes.put(name, value);
@@ -529,6 +540,7 @@ public class MockServletContext implements ServletContext {
 	}
 
 	@Override
+	@Nullable
 	public ClassLoader getClassLoader() {
 		return ClassUtils.getDefaultClassLoader();
 	}
@@ -579,21 +591,23 @@ public class MockServletContext implements ServletContext {
 	}
 
 	@Override  // on Servlet 4.0
-	public void setRequestCharacterEncoding(String requestCharacterEncoding) {
+	public void setRequestCharacterEncoding(@Nullable String requestCharacterEncoding) {
 		this.requestCharacterEncoding = requestCharacterEncoding;
 	}
 
 	@Override  // on Servlet 4.0
+	@Nullable
 	public String getRequestCharacterEncoding() {
 		return this.requestCharacterEncoding;
 	}
 
 	@Override  // on Servlet 4.0
-	public void setResponseCharacterEncoding(String responseCharacterEncoding) {
+	public void setResponseCharacterEncoding(@Nullable String responseCharacterEncoding) {
 		this.responseCharacterEncoding = responseCharacterEncoding;
 	}
 
 	@Override  // on Servlet 4.0
+	@Nullable
 	public String getResponseCharacterEncoding() {
 		return this.responseCharacterEncoding;
 	}
@@ -638,6 +652,7 @@ public class MockServletContext implements ServletContext {
 	 * @see javax.servlet.ServletContext#getServletRegistration(java.lang.String)
 	 */
 	@Override
+	@Nullable
 	public ServletRegistration getServletRegistration(String servletName) {
 		return null;
 	}
@@ -676,6 +691,7 @@ public class MockServletContext implements ServletContext {
 	 * @see javax.servlet.ServletContext#getFilterRegistration(java.lang.String)
 	 */
 	@Override
+	@Nullable
 	public FilterRegistration getFilterRegistration(String filterName) {
 		return null;
 	}
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/MockSessionCookieConfig.java b/spring-web/src/test/java/org/springframework/mock/web/test/MockSessionCookieConfig.java
index 5933d2c781..5f4e1326e9 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/MockSessionCookieConfig.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/MockSessionCookieConfig.java
@@ -18,6 +18,8 @@ package org.springframework.mock.web.test;
 
 import javax.servlet.SessionCookieConfig;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Mock implementation of the {@link javax.servlet.SessionCookieConfig} interface.
  *
@@ -27,12 +29,16 @@ import javax.servlet.SessionCookieConfig;
  */
 public class MockSessionCookieConfig implements SessionCookieConfig {
 
+	@Nullable
 	private String name;
 
+	@Nullable
 	private String domain;
 
+	@Nullable
 	private String path;
 
+	@Nullable
 	private String comment;
 
 	private boolean httpOnly;
@@ -43,41 +49,45 @@ public class MockSessionCookieConfig implements SessionCookieConfig {
 
 
 	@Override
-	public void setName(String name) {
+	public void setName(@Nullable String name) {
 		this.name = name;
 	}
 
 	@Override
+	@Nullable
 	public String getName() {
 		return this.name;
 	}
 
 	@Override
-	public void setDomain(String domain) {
+	public void setDomain(@Nullable String domain) {
 		this.domain = domain;
 	}
 
 	@Override
+	@Nullable
 	public String getDomain() {
 		return this.domain;
 	}
 
 	@Override
-	public void setPath(String path) {
+	public void setPath(@Nullable String path) {
 		this.path = path;
 	}
 
 	@Override
+	@Nullable
 	public String getPath() {
 		return this.path;
 	}
 
 	@Override
-	public void setComment(String comment) {
+	public void setComment(@Nullable String comment) {
 		this.comment = comment;
 	}
 
 	@Override
+	@Nullable
 	public String getComment() {
 		return this.comment;
 	}
diff --git a/spring-web/src/test/java/org/springframework/mock/web/test/PassThroughFilterChain.java b/spring-web/src/test/java/org/springframework/mock/web/test/PassThroughFilterChain.java
index 3fb2b44a93..412492b7e7 100644
--- a/spring-web/src/test/java/org/springframework/mock/web/test/PassThroughFilterChain.java
+++ b/spring-web/src/test/java/org/springframework/mock/web/test/PassThroughFilterChain.java
@@ -24,6 +24,7 @@ import javax.servlet.ServletException;
 import javax.servlet.ServletRequest;
 import javax.servlet.ServletResponse;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -40,10 +41,13 @@ import org.springframework.util.Assert;
  */
 public class PassThroughFilterChain implements FilterChain {
 
+	@Nullable
 	private Filter filter;
 
+	@Nullable
 	private FilterChain nextFilterChain;
 
+	@Nullable
 	private Servlet servlet;