/// <summary>
        /// Adds an unknown property to the vertex type definition
        /// </summary>
        /// <param name="myUnknownPredefinition">The unknwown property definition that is going to be added</param>
        /// <returns>The reference of the current object. (fluent interface).</returns>
        public VertexTypePredefinition AddUnknownAttribute(UnknownAttributePredefinition myUnknownPredefinition)
        {
            if (myUnknownPredefinition != null)
            {
                _attributes = (_attributes) ?? new List<AttributePredefinition>();
                _attributes.Add(myUnknownPredefinition);
                _unknown++;
            }

            return this;
        }
        /// <summary>
        /// Adds an unknown property to the vertex type definition
        /// </summary>
        /// <param name="myUnknownPredefinition">The unknwown property definition that is going to be added</param>
        /// <returns>The reference of the current object. (fluent interface).</returns>
        public RequestAlterVertexType AddUnknownAttribute(UnknownAttributePredefinition myUnknownPredefinition)
        {
            if (myUnknownPredefinition != null)
            {
                _toBeAddedAttributes = (_toBeAddedAttributes) ?? new List<AttributePredefinition>();
                _toBeAddedAttributes.Add(myUnknownPredefinition);
                AddUnknownPropertyCount++;
            }

            return this;
        }