System.Data.Common.DbConnectionStringBuilder.ContainsKey C# (CSharp) Метод

        public virtual bool ContainsKey(string keyword)
        {
            ADP.CheckArgumentNull(keyword, nameof(keyword));
            return CurrentValues.ContainsKey(keyword);
        }

 public void Initialize(string connectionString)
 {
     var parser = new DbConnectionStringBuilder {ConnectionString = connectionString};
     var fileName = parser.ContainsKey("Filename")
         ? parser["Filename"].ToString()
         : Path.Combine(Directory.GetCurrentDirectory(), "PlayPass.log");
     var appendMode = !parser.ContainsKey("Append") || (parser["Append"].ToString() == "1");
     _file = new StreamWriter(fileName, appendMode) {AutoFlush = true};
 }