Abort search for static methods in getPubliclyAccessibleMethodIfPossible()

Prior to this commit, getPubliclyAccessibleMethodIfPossible() in
ClassUtils incorrectly returned a hidden static method as an
"equivalent" method for a static method with the same signature;
however, a static method cannot be overridden and therefore has no
"equivalent" method in a super type.

To fix that bug, this commit immediately aborts the search for an
"equivalent" publicly accessible method when the original method is a
static method.

See gh-33216
See gh-35189
See gh-35556
Closes gh-35667

spring-core/src/test/java/org/springframework/util/ClassUtilsTests.java

@@ -868,6 +868,49 @@ class ClassUtilsTests {
 			assertPubliclyAccessible(publiclyAccessibleMethod);
 		}
 
+		@Test  // gh-35667
+		void staticMethodInPublicClass() throws Exception {
+			Method originalMethod = PublicSuperclass.class.getMethod("getCacheKey");
+
+			// Prerequisite: method must be public static for this use case.
+			assertPublic(originalMethod);
+			assertStatic(originalMethod);
+
+			Method publiclyAccessibleMethod = ClassUtils.getPubliclyAccessibleMethodIfPossible(originalMethod, null);
+			assertThat(publiclyAccessibleMethod).isSameAs(originalMethod);
+			assertPubliclyAccessible(publiclyAccessibleMethod);
+		}
+
+		@Test  // gh-35667
+		void publicSubclassHidesStaticMethodInPublicSuperclass() throws Exception {
+			Method originalMethod = PublicSubclass.class.getMethod("getCacheKey");
+
+			// Prerequisite: type must be public for this use case.
+			assertPublic(originalMethod.getDeclaringClass());
+			// Prerequisite: method must be public static for this use case.
+			assertPublic(originalMethod);
+			assertStatic(originalMethod);
+
+			Method publiclyAccessibleMethod = ClassUtils.getPubliclyAccessibleMethodIfPossible(originalMethod, null);
+			assertThat(publiclyAccessibleMethod).isSameAs(originalMethod);
+			assertPubliclyAccessible(publiclyAccessibleMethod);
+		}
+
+		@Test  // gh-35667
+		void privateSubclassHidesStaticMethodInPublicSuperclass() throws Exception {
+			Method originalMethod = PrivateSubclass.class.getMethod("getCacheKey");
+
+			// Prerequisite: type must not be public for this use case.
+			assertNotPublic(originalMethod.getDeclaringClass());
+			// Prerequisite: method must be public static for this use case.
+			assertPublic(originalMethod);
+			assertStatic(originalMethod);
+
+			Method publiclyAccessibleMethod = ClassUtils.getPubliclyAccessibleMethodIfPossible(originalMethod, null);
+			assertThat(publiclyAccessibleMethod).isSameAs(originalMethod);
+			assertNotPubliclyAccessible(publiclyAccessibleMethod);
+		}
+
 	}
 
 
@@ -914,6 +957,10 @@ class ClassUtilsTests {
 		return Modifier.isPublic(member.getModifiers());
 	}
 
+	private static void assertStatic(Member member) {
+		assertThat(Modifier.isStatic(member.getModifiers())).as("%s must be static", member).isTrue();
+	}
+
 
 	@Target(ElementType.METHOD)
 	@Retention(RetentionPolicy.RUNTIME)
@@ -1048,8 +1095,27 @@ class ClassUtilsTests {
 		String greet(String name);
 	}
 
+	public static class PublicSubclass extends PublicSuperclass {
+
+		/**
+		 * This method intentionally has the exact same signature as
+		 * {@link PublicSuperclass#getCacheKey()}.
+		 */
+		public static String getCacheKey() {
+			return "child";
+		}
+	}
+
 	private static class PrivateSubclass extends PublicSuperclass implements PublicInterface, PrivateInterface {
 
+		/**
+		 * This method intentionally has the exact same signature as
+		 * {@link PublicSuperclass#getCacheKey()}.
+		 */
+		public static String getCacheKey() {
+			return "child";
+		}
+
 		@Override
 		public int getNumber() {
 			return 2;

spring-core/src/test/java/org/springframework/util/PublicSuperclass.java

@@ -21,6 +21,15 @@ package org.springframework.util;
  */
 public class PublicSuperclass {
 
+	/**
+	 * This method intentionally has the exact same signature as
+	 * {@link org.springframework.util.ClassUtilsTests.PublicSubclass#getCacheKey()} and
+	 * {@link org.springframework.util.ClassUtilsTests.PrivateSubclass#getCacheKey()}.
+	 */
+	public static String getCacheKey() {
+		return "parent";
+	}
+
 	public String getMessage() {
 		return "goodbye";
 	}