Annotate Object#equals parameter with @Nullable

Closes gh-23093

spring-test/src/main/java/org/springframework/test/context/ContextConfigurationAttributes.java

@@ -331,7 +331,7 @@ public class ContextConfigurationAttributes {
 	 * {@link #getContextLoaderClass() ContextLoader class}.
 	 */
 	@Override
-	public boolean equals(Object other) {
+	public boolean equals(@Nullable Object other) {
 		if (this == other) {
 			return true;
 		}

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

@@ -20,6 +20,7 @@ import java.util.function.Consumer;
 
 import org.hamcrest.Matcher;
 
+import org.springframework.lang.Nullable;
 import org.springframework.test.util.JsonPathExpectationsHelper;
 
 /**
@@ -178,7 +179,7 @@ public class JsonPathAssertions {
 
 
 	@Override
-	public boolean equals(Object obj) {
+	public boolean equals(@Nullable Object obj) {
 		throw new AssertionError("Object#equals is disabled " +
 				"to avoid being used in error instead of JsonPathAssertions#isEqualTo(String).");
 	}