@Override
    default Function<ENTITY, V> asFunction() {
        return this;
    }
A short-cut functional reference to the {@code getXXX()} method for a
particular field in an entity.
<p>
A {@code ReferenceGetter<ENTITY, V>} has the following signature:
{@code
     interface ENTITY {
         V getXXX();
     }
}

@param <ENTITY>  the entity
@param <V>       the type of the value to return

@author  Emil Forslund
@since   2.2.0
runtime-parent/runtime-field/src/main/java/com/speedment/runtime/field/method/ReferenceGetter.java