/// <summary>
        /// Check if property is not null.
        /// </summary>
        /// <returns>Current instance.</returns>
        public PropertyValidator <TRow> IsNotNull()
        {
            StringRule <TRow> method = new StringRule <TRow>((x) => this.getter(x));

            method.IsNotNull();
            this.validationRules.Add(method);
            return(this);
        }