static idExists(id) {
        return this.exists({
            [this.idAttribute]: id,
        });
    }
Returns a boolean indicating if an entity
with the id `id` exists in the state.

@param  {*}  id - a value corresponding to the id attribute of the {@link Model} class.
@return {Boolean} a boolean indicating if entity with `id` exists in the state

@since 0.11.0