Update code due to change in nullability contract

See gh-34933

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.http.client;
 import java.io.IOException;
 import java.io.InputStream;
 import java.net.HttpURLConnection;
+import java.util.Objects;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatusCode;
@@ -103,6 +104,7 @@ final class SimpleClientHttpResponse implements ClientHttpResponse {
 			if (this.responseStream == null) {
 				getBody();
 			}
+			Objects.requireNonNull(this.responseStream);
 			StreamUtils.drain(this.responseStream);
 			this.responseStream.close();
 		}