diff --git a/build.gradle b/build.gradle
index 87cb8892823..aafb9a6c5e8 100644
--- a/build.gradle
+++ b/build.gradle
@@ -46,7 +46,7 @@ ext {
 	rxjava2Version       = "2.2.7"
 	slf4jVersion         = "1.7.26"	  // spring-jcl + consistent 3rd party deps
 	tiles3Version        = "3.0.8"
-	tomcatVersion        = "9.0.16"
+	tomcatVersion        = "9.0.17"
 	undertowVersion      = "2.0.19.Final"
 
 	gradleScriptDir = "${rootProject.projectDir}/gradle"
diff --git a/spring-core/src/main/java/org/springframework/util/StringUtils.java b/spring-core/src/main/java/org/springframework/util/StringUtils.java
index 093fa9d404c..11e33cbbce1 100644
--- a/spring-core/src/main/java/org/springframework/util/StringUtils.java
+++ b/spring-core/src/main/java/org/springframework/util/StringUtils.java
@@ -780,7 +780,9 @@ public abstract class StringUtils {
 		if (tokens.length == 1) {
 			validateLocalePart(localeValue);
 			Locale resolved = Locale.forLanguageTag(localeValue);
-			return (resolved.getLanguage().length() > 0 ? resolved : null);
+			if (resolved.getLanguage().length() > 0) {
+				return resolved;
+			}
 		}
 		return parseLocaleTokens(localeValue, tokens);
 	}
diff --git a/spring-core/src/test/java/org/springframework/util/StringUtilsTests.java b/spring-core/src/test/java/org/springframework/util/StringUtilsTests.java
index ab0e294d214..8b77c0b2717 100644
--- a/spring-core/src/test/java/org/springframework/util/StringUtilsTests.java
+++ b/spring-core/src/test/java/org/springframework/util/StringUtilsTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -765,4 +765,20 @@ public class StringUtilsTests {
 		}
 	}
 
+	@Test
+	public void testInvalidLocaleWithLocaleString() {
+		assertEquals(new Locale("invalid"), StringUtils.parseLocaleString("invalid"));
+		assertEquals(new Locale("invalidvalue"), StringUtils.parseLocaleString("invalidvalue"));
+		assertEquals(new Locale("invalidvalue", "foo"), StringUtils.parseLocaleString("invalidvalue_foo"));
+		assertNull(StringUtils.parseLocaleString(""));
+	}
+
+	@Test
+	public void testInvalidLocaleWithLanguageTag() {
+		assertEquals(new Locale("invalid"), StringUtils.parseLocale("invalid"));
+		assertEquals(new Locale("invalidvalue"), StringUtils.parseLocale("invalidvalue"));
+		assertEquals(new Locale("invalidvalue", "foo"), StringUtils.parseLocale("invalidvalue_foo"));
+		assertNull(StringUtils.parseLocale(""));
+	}
+
 }
diff --git a/spring-web/spring-web.gradle b/spring-web/spring-web.gradle
index 03bad1cb077..f9e063b98bb 100644
--- a/spring-web/spring-web.gradle
+++ b/spring-web/spring-web.gradle
@@ -38,7 +38,7 @@ dependencies {
 		exclude group: "javax.servlet", module: "javax.servlet-api"
 	}
 	optional("org.eclipse.jetty:jetty-reactive-httpclient:1.0.2")
-	optional("com.squareup.okhttp3:okhttp:3.13.1")
+	optional("com.squareup.okhttp3:okhttp:3.14.0")
 	optional("org.apache.httpcomponents:httpclient:4.5.7") {
 		exclude group: "commons-logging", module: "commons-logging"
 	}
@@ -75,7 +75,7 @@ dependencies {
 	testCompile("org.apache.tomcat.embed:tomcat-embed-core:${tomcatVersion}")
 	testCompile("org.eclipse.jetty:jetty-server")
 	testCompile("org.eclipse.jetty:jetty-servlet")
-	testCompile("com.squareup.okhttp3:mockwebserver:3.13.1")
+	testCompile("com.squareup.okhttp3:mockwebserver:3.14.0")
 	testCompile("org.jetbrains.kotlin:kotlin-reflect:${kotlinVersion}")
 	testCompile("org.skyscreamer:jsonassert:1.5.0")
 	testCompile("org.xmlunit:xmlunit-matchers:2.6.2")
diff --git a/spring-webflux/spring-webflux.gradle b/spring-webflux/spring-webflux.gradle
index 90f0f883985..3d8c26f1bc9 100644
--- a/spring-webflux/spring-webflux.gradle
+++ b/spring-webflux/spring-webflux.gradle
@@ -53,7 +53,7 @@ dependencies {
 	testCompile("org.eclipse.jetty:jetty-server")
 	testCompile("org.eclipse.jetty:jetty-servlet")
 	testCompile("org.eclipse.jetty:jetty-reactive-httpclient:1.0.2")
-	testCompile("com.squareup.okhttp3:mockwebserver:3.13.1")
+	testCompile("com.squareup.okhttp3:mockwebserver:3.14.0")
 	testCompile("org.jetbrains.kotlin:kotlin-script-runtime:${kotlinVersion}")
 	testRuntime("org.jetbrains.kotlin:kotlin-script-util:${kotlinVersion}")
 	testRuntime("org.jetbrains.kotlin:kotlin-compiler:${kotlinVersion}")
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseEntityExceptionHandler.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseEntityExceptionHandler.java
index 0710ab65ec5..40e269194cb 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseEntityExceptionHandler.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseEntityExceptionHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -446,7 +446,7 @@ public abstract class ResponseEntityExceptionHandler {
 	}
 
 	/**
-	 * A single place to customize the response body of all Exception types.
+	 * A single place to customize the response body of all exception types.
 	 * <p>The default implementation sets the {@link WebUtils#ERROR_EXCEPTION_ATTRIBUTE}
 	 * request attribute and creates a {@link ResponseEntity} from the given
 	 * body, headers, and status.