From 87d3d1bbd1e5620fb8c2583c487507bab9614fb2 Mon Sep 17 00:00:00 2001
From: Sam Brannen <sbrannen@vmware.com>
Date: Mon, 6 Sep 2021 16:52:23 +0200
Subject: [PATCH] Throw UnsupportedOperationException in
 defaultResponseCharacterEncoding()

This commit updates the defaultResponseCharacterEncoding() `default`
method in ConfigurableMockMvcBuilder so that it throws an
UnsupportedOperationException instead of silently ignoring the user's
request to set the default response character encoding.

Note, however, that AbstractMockMvcBuilder already overrides the
default method with a concrete implementation which is used by default
in MockMvc.

See gh-27230
---
 .../web/servlet/setup/ConfigurableMockMvcBuilder.java     | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/spring-test/src/main/java/org/springframework/test/web/servlet/setup/ConfigurableMockMvcBuilder.java b/spring-test/src/main/java/org/springframework/test/web/servlet/setup/ConfigurableMockMvcBuilder.java
index 43ef6ca954..145dccc8a3 100644
--- a/spring-test/src/main/java/org/springframework/test/web/servlet/setup/ConfigurableMockMvcBuilder.java
+++ b/spring-test/src/main/java/org/springframework/test/web/servlet/setup/ConfigurableMockMvcBuilder.java
@@ -86,14 +86,14 @@ public interface ConfigurableMockMvcBuilder<B extends ConfigurableMockMvcBuilder
 
 	/**
 	 * Define the default character encoding to be applied to every response.
-	 * <p>The default implementation of this method ignores the supplied value.
-	 * Concrete implementations are therefore encouraged to override this method.
+	 * <p>The default implementation of this method throws an
+	 * {@link UnsupportedOperationException}. Concrete implementations are therefore
+	 * encouraged to override this method.
 	 * @param defaultResponseCharacterEncoding the default response character encoding
 	 * @since 5.3.10
 	 */
-	@SuppressWarnings("unchecked")
 	default <T extends B> T defaultResponseCharacterEncoding(Charset defaultResponseCharacterEncoding) {
-		return (T) this;
+		throw new UnsupportedOperationException();
 	}
 
 	/**