Get generic field type at runtime via reflection

I am having trouble accessing the runtime type of id via reflection from MyClass.

public abstract class AbstractEntity<T> {

    @Id
    private T id; //I need to access the runtime class of T

}

public class MyClass extends AbstractEntity<Long> {} 

I am using java reflection and have access to the id Field in the superclass.

I tried using:

• field.getGenericType(): which returns TypeVariableImpl with a value T.
• field.getType() which returns Object.

I want to access Long as the field type.

I am writing a library for others to use and there are a few issues:

1. I don't actually know if the type is a generic type or a regular type, I only know it is annotated with @id.
2. I don't know where in the class hierarchy this field is located.

Here is the method I am using to get hold of all fields in the class hierarchy.

private Set<Field> getAllFields(final Object object) {
    final Set<Field> fields = new HashSet<>();
    fields.addAll(Arrays.asList(object.getClass().getDeclaredFields()));
    Class<?> superclass = object.getClass().getSuperclass();
    while (superclass != null) {
        fields.addAll(Arrays.asList(superclass.getDeclaredFields()));
        superclass = superclass.getSuperclass();
    }
    return fields;
}

I then filter this list for field annotated with @Id of which there should only be one.