Polish contribution

- Split Validator::of into two factory methods:
  - forInstanceOf using Class::isAssignableFrom
  - forType using Class::equals
- Moved anonymous implementation into TypedValidator with default access

Closes gh-30341

spring-context/src/test/java/org/springframework/validation/DataBinderTests.java

@@ -82,7 +82,7 @@ import static org.assertj.core.api.Assertions.entry;
  */
 class DataBinderTests {
 
-	Validator spouseValidator = Validator.of(TestBean.class, (tb, errors) -> {
+	private final Validator spouseValidator = Validator.forInstanceOf(TestBean.class, (tb, errors) -> {
 				if (tb == null || "XXX".equals(tb.getName())) {
 					errors.rejectValue("", "SPOUSE_NOT_AVAILABLE");
 					return;

spring-context/src/test/java/org/springframework/validation/ValidationUtilsTests.java

@@ -33,9 +33,9 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  */
 public class ValidationUtilsTests {
 
-	Validator emptyValidator = Validator.of(TestBean.class, (testBean, errors) -> ValidationUtils.rejectIfEmpty(errors, "name", "EMPTY", "You must enter a name!"));
+	private final Validator emptyValidator = Validator.forInstanceOf(TestBean.class, (testBean, errors) -> ValidationUtils.rejectIfEmpty(errors, "name", "EMPTY", "You must enter a name!"));
 
-	Validator emptyOrWhitespaceValidator = Validator.of(TestBean.class, (testBean, errors) -> ValidationUtils.rejectIfEmptyOrWhitespace(errors, "name", "EMPTY_OR_WHITESPACE", "You must enter a name!"));
+	private final Validator emptyOrWhitespaceValidator = Validator.forInstanceOf(TestBean.class, (testBean, errors) -> ValidationUtils.rejectIfEmptyOrWhitespace(errors, "name", "EMPTY_OR_WHITESPACE", "You must enter a name!"));
 
 	@Test
 	public void testInvokeValidatorWithNullValidator() throws Exception {

spring-context/src/test/java/org/springframework/validation/ValidatorTests.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2002-2023 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.validation;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.testfixture.beans.TestBean;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Arjen Poutsma
+ */
+class ValidatorTests {
+
+	@Test
+	public void testSupportsForInstanceOf() {
+		Validator validator = Validator.forInstanceOf(TestBean.class, (testBean, errors) -> {});
+		assertThat(validator.supports(TestBean.class)).isTrue();
+		assertThat(validator.supports(TestBeanSubclass.class)).isTrue();
+	}
+
+	@Test
+	public void testSupportsForType() {
+		Validator validator = Validator.forType(TestBean.class, (testBean, errors) -> {});
+		assertThat(validator.supports(TestBean.class)).isTrue();
+		assertThat(validator.supports(TestBeanSubclass.class)).isFalse();
+	}
+
+
+	private static class TestBeanSubclass extends TestBean {
+	}
+
+}