Dynamic enum with OpenJDK 11 using reflection

I'm working on a project running with JDK8 and we want to migrate it to OpenJDK11.

But, there is legacy code that creates enums dynamically at runtime (using reflection and sun.reflect.* packages) :

enumClass.cast(sun.reflect.ReflectionFactory.getReflectionFactory().newConstructorAccessor(constructor).newInstance(params));

Or

    // before, field is made accessible, the modifier too
    sun.reflect.FieldAccessor fieldAccessor = sun.reflect.ReflectionFactory.getReflectionFactory().newFieldAccessor(field, false);
    field.set(target, value);

Unfortunately, sun.reflect.* classes are no longer available in OpenJDK11.

I've tried using jdk.internal.reflect.ConstructorAccessor but I'm getting the error java: package jdk.internal.reflect does not exist. And I don't think it's a good idea to rely on jdk.internal.* classes.

Is there any OpenJDK11 alternative to create enums at runtime ?