Uses MethodHandle to access private package

PrivateConstructors.java

public abstract class PrivateConstructors {
    // public class CustomIterable<V> implements Iterable<V> {
    //   CustomIterable() {}
    // }

    
    @SuppressWarnings("unchecked")
    private static <I extends T, T> I newInstanceOf(Class<T> clazz) throws Throwable {
        MethodHandles.Lookup lookup = MethodHandles.privateLookupIn(clazz, MethodHandles.lookup());
        MethodHandle methodHandle = lookup.findConstructor(clazz, MethodType.methodType(void.class));
        Supplier<T> constructor = (Supplier<T>) LambdaMetafactory.metafactory(
                lookup,
                "get",
                MethodType.methodType(Supplier.class),
                methodHandle.type().generic(),
                methodHandle,
                methodHandle.type()
        ).getTarget().invokeExact();
        return (I) constructor.get();
    }
}