Reject JDK proxy hint registration for sealed interfaces

Closes gh-28786

Author: sbrannen

Diff for: spring-core/src/main/java/org/springframework/aot/hint/JdkProxyHint.java

@@ -151,10 +151,12 @@ JdkProxyHint build() {
 		}
 
 		private static List<TypeReference> toTypeReferences(Class<?>... proxiedInterfaces) {
-			List<String> concreteTypes = Arrays.stream(proxiedInterfaces)
-					.filter(candidate -> !candidate.isInterface()).map(Class::getName).toList();
-			if (!concreteTypes.isEmpty()) {
-				throw new IllegalArgumentException("Not an interface: " + concreteTypes);
+			List<String> invalidTypes = Arrays.stream(proxiedInterfaces)
+					.filter(candidate -> !candidate.isInterface() || candidate.isSealed())
+					.map(Class::getName)
+					.toList();
+			if (!invalidTypes.isEmpty()) {
+				throw new IllegalArgumentException("The following must be non-sealed interfaces: " + invalidTypes);
 			}
 			return Arrays.stream(proxiedInterfaces).map(TypeReference::of).toList();
 		}

Diff for: spring-core/src/test/java/org/springframework/aot/hint/ProxyHintsTests.java

@@ -39,17 +39,25 @@ class ProxyHintsTests {
 
 
 	@Test
-	void registerJdkProxyWithInterfaceClass() {
-		this.proxyHints.registerJdkProxy(Function.class);
-		assertThat(this.proxyHints.jdkProxies()).singleElement().satisfies(proxiedInterfaces(Function.class));
+	void registerJdkProxyWithSealedInterface() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> this.proxyHints.registerJdkProxy(SealedInterface.class))
+				.withMessageContaining(SealedInterface.class.getName());
 	}
 
 	@Test
 	void registerJdkProxyWithConcreteClass() {
-		assertThatIllegalArgumentException().isThrownBy(() -> this.proxyHints.registerJdkProxy(String.class))
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> this.proxyHints.registerJdkProxy(String.class))
 				.withMessageContaining(String.class.getName());
 	}
 
+	@Test
+	void registerJdkProxyWithInterface() {
+		this.proxyHints.registerJdkProxy(Function.class);
+		assertThat(this.proxyHints.jdkProxies()).singleElement().satisfies(proxiedInterfaces(Function.class));
+	}
+
 	@Test
 	void registerJdkProxyWithTypeReferences() {
 		this.proxyHints.registerJdkProxy(TypeReference.of(Function.class), TypeReference.of("com.example.Advised"));
@@ -128,4 +136,11 @@ private static TypeReference[] toTypeReferences(Class<?>... proxiedInterfaces) {
 		return Arrays.stream(proxiedInterfaces).map(TypeReference::of).toArray(TypeReference[]::new);
 	}
 
+
+	sealed interface SealedInterface {
+	}
+
+	static final class SealedClass implements SealedInterface {
+	}
+
 }