@SuppressWarnings("unchecked")
    private static <I, R> Function<I, R> castingIdentity() {
        return i -> (R) i;
    }
@param <T>  the entity type to be collected
@param <A>  the intermediate accumulation type of the downstream collector
@param <R>  the collected result

@author Emil Forslund
@since  3.0.2
runtime-parent/runtime-field/src/main/java/com/speedment/runtime/field/internal/collector/FieldCollectorImpl.java