Avoid nullability warnings

spring-test/src/main/java/org/springframework/test/web/reactive/server/CookieAssertions.java

@@ -17,6 +17,7 @@
 package org.springframework.test.web.reactive.server;
 
 import java.time.Duration;
+import java.util.Objects;
 import java.util.function.Consumer;
 
 import org.hamcrest.Matcher;
@@ -210,10 +211,10 @@ public class CookieAssertions {
 	private ResponseCookie getCookie(String name) {
 		ResponseCookie cookie = this.exchangeResult.getResponseCookies().getFirst(name);
 		if (cookie == null) {
-			String message = "No cookie with name '" + name + "'";
-			this.exchangeResult.assertWithDiagnostics(() -> AssertionErrors.fail(message));
+			this.exchangeResult.assertWithDiagnostics(() ->
+					AssertionErrors.fail("No cookie with name '" + name + "'"));
 		}
-		return cookie;
+		return Objects.requireNonNull(cookie);
 	}
 
 	private String getMessage(String cookie) {

spring-test/src/main/java/org/springframework/test/web/reactive/server/HeaderAssertions.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2021 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.test.web.reactive.server;
 import java.net.URI;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 import java.util.function.Consumer;
 
 import org.hamcrest.Matcher;
@@ -73,7 +74,7 @@ public class HeaderAssertions {
 		String actual = getHeaders().getFirst(headerName);
 		this.exchangeResult.assertWithDiagnostics(() ->
 				assertTrue("Response does not contain header '" + headerName + "'", actual != null));
-		return assertHeader(headerName, value, Long.parseLong(actual));
+		return assertHeader(headerName, value, Long.parseLong(Objects.requireNonNull(actual)));
 	}
 
 	/**
@@ -203,7 +204,7 @@ public class HeaderAssertions {
 			this.exchangeResult.assertWithDiagnostics(() ->
 					AssertionErrors.fail(getMessage(name) + " not found"));
 		}
-		return values;
+		return Objects.requireNonNull(values);
 	}
 
 	/**