Restore support for package private ReflectiveProcessor

See gh-28975

spring-core/src/main/java/org/springframework/aot/hint/annotation/ReflectiveRuntimeHintsRegistrar.java

@@ -113,7 +113,9 @@ private Entry createEntry(AnnotatedElement element) {
 
 	private ReflectiveProcessor instantiateClass(Class<? extends ReflectiveProcessor> type) {
 		try {
-			return type.getDeclaredConstructor().newInstance();
+			Constructor<? extends ReflectiveProcessor> constructor = type.getDeclaredConstructor();
+			ReflectionUtils.makeAccessible(constructor);
+			return constructor.newInstance();
 		}
 		catch (Exception ex) {
 			throw new IllegalStateException("Failed to instantiate " + type, ex);

spring-core/src/test/java/org/springframework/aot/hint/annotation/ReflectiveRuntimeHintsRegistrarTests.java

@@ -21,9 +21,12 @@
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
+import java.lang.reflect.Method;
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.ReflectionHints;
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.TypeReference;
 import org.springframework.aot.hint.predicate.RuntimeHintsPredicates;
@@ -121,6 +124,16 @@ void shouldProcessAnnotationOnInheritedClass() {
 						.satisfies(methodHint -> assertThat(methodHint.getName()).isEqualTo("managed")));
 	}
 
+	@Test
+	void shouldInvokeCustomProcessor() {
+		process(SampleCustomProcessor.class);
+		assertThat(RuntimeHintsPredicates.reflection()
+				.onMethod(SampleCustomProcessor.class, "managed")).accepts(this.runtimeHints);
+		assertThat(RuntimeHintsPredicates.reflection().onType(String.class)
+				.withMemberCategory(MemberCategory.INVOKE_DECLARED_METHODS)).accepts(this.runtimeHints);
+
+	}
+
 	private void process(Class<?> beanClass) {
 		this.registrar.registerRuntimeHints(this.runtimeHints, beanClass);
 	}
@@ -252,4 +265,24 @@ void managed() {
 		}
 	}
 
+	static class SampleCustomProcessor {
+
+		@Reflective(TestReflectiveProcessor.class)
+		public String managed() {
+			return "test";
+		}
+
+	}
+
+	private static class TestReflectiveProcessor extends SimpleReflectiveProcessor {
+
+		@Override
+		protected void registerMethodHint(ReflectionHints hints, Method method) {
+			super.registerMethodHint(hints, method);
+			hints.registerType(method.getReturnType(), type ->
+					type.withMembers(MemberCategory.INVOKE_DECLARED_METHODS));
+		}
+
+	}
+
 }