Reject write methods not starting with "set" in Property

spring-core/src/main/java/org/springframework/core/convert/Property.java

@@ -150,12 +150,11 @@ private String resolveName() {
 			return StringUtils.uncapitalize(this.readMethod.getName().substring(index));
 		}
 		else if (this.writeMethod != null) {
-			int index = this.writeMethod.getName().indexOf("set");
-			if (index == -1) {
+			String methodName = this.writeMethod.getName();
+			if (!methodName.startsWith("set")) {
 				throw new IllegalArgumentException("Not a setter method");
 			}
-			index += 3;
-			return StringUtils.uncapitalize(this.writeMethod.getName().substring(index));
+			return StringUtils.uncapitalize(methodName.substring(3));
 		}
 		else {
 			throw new IllegalStateException("Property is neither readable nor writable");

spring-core/src/test/java/org/springframework/core/convert/PropertyTests.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2002-present 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.core.convert;
+
+import java.lang.reflect.Method;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+
+/**
+ * Tests for {@link Property} setter name resolution.
+ *
+ * @author Junhyeong Kim
+ */
+class PropertyTests {
+
+	@Test
+	void resolveNameForSetter() throws Exception {
+		assertThat(writeProperty("setName").getName()).isEqualTo("name");
+	}
+
+	@Test  // no "set" token at all: rejected before and after this change
+	void rejectNonSetterWriteMethod() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> writeProperty("updateName"))
+				.withMessage("Not a setter method");
+	}
+
+	@Test  // "set" embedded mid-name: formerly accepted and resolved to "x"
+	void rejectWriteMethodEmbeddingSetInName() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> writeProperty("offsetX"))
+				.withMessage("Not a setter method");
+	}
+
+	@Test  // "set" at the end of the name: formerly accepted and resolved to ""
+	void rejectWriteMethodEndingWithSetToken() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> writeProperty("upset"))
+				.withMessage("Not a setter method");
+	}
+
+
+	private static Property writeProperty(String writeMethodName) throws Exception {
+		Method writeMethod = TestBean.class.getMethod(writeMethodName, String.class);
+		return new Property(TestBean.class, null, writeMethod);
+	}
+
+
+	@SuppressWarnings("unused")
+	static class TestBean {
+
+		public void setName(String name) {
+		}
+
+		public void updateName(String name) {
+		}
+
+		public void offsetX(String value) {
+		}
+
+		public void upset(String value) {
+		}
+	}
+
+}