Add equals/hashCode methods to ProblemDetail

Closes gh-29606

spring-web/src/test/java/org/springframework/http/ProblemDetailTests.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2002-2022 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.http;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Unit tests for {@link ProblemDetail}.
+ *
+ * @author Juergen Hoeller
+ */
+class ProblemDetailTests {
+
+	@Test
+	void equalsAndHashCode() {
+		ProblemDetail pd1 = ProblemDetail.forStatus(500);
+		ProblemDetail pd2 = ProblemDetail.forStatus(HttpStatus.INTERNAL_SERVER_ERROR);
+		ProblemDetail pd3 = ProblemDetail.forStatus(HttpStatus.NOT_FOUND);
+		ProblemDetail pd4 = ProblemDetail.forStatusAndDetail(HttpStatus.NOT_FOUND, "some detail");
+
+		assertThat(pd1).isEqualTo(pd2);
+		assertThat(pd2).isEqualTo(pd1);
+		assertThat(pd1.hashCode()).isEqualTo(pd2.hashCode());
+
+		assertThat(pd3).isNotEqualTo(pd4);
+		assertThat(pd4).isNotEqualTo(pd3);
+		assertThat(pd3.hashCode()).isNotEqualTo(pd4.hashCode());
+
+		assertThat(pd1).isNotEqualTo(pd3);
+		assertThat(pd1).isNotEqualTo(pd4);
+		assertThat(pd2).isNotEqualTo(pd3);
+		assertThat(pd2).isNotEqualTo(pd4);
+		assertThat(pd1.hashCode()).isNotEqualTo(pd3.hashCode());
+		assertThat(pd1.hashCode()).isNotEqualTo(pd4.hashCode());
+	}
+
+}