CED.MainForm.AddToCollection C# (CSharp) Method

        private StringCollection AddToCollection(StringCollection collection, TextBox textBox)
        {
            if (collection == null)
            {
                collection = new StringCollection();
            }

            if (!string.IsNullOrEmpty(textBox.Text) && !collection.Contains(textBox.Text))
            {
                collection.Add(textBox.Text);
                AutoCompleteConfigure(textBox, collection);

            }

            return collection;
        }