/// <summary>
 /// Initializes a new instance of <see cref="FlatFileTraceListener"/> with a file name, a header, a footer and
 /// a <see cref="ILogFormatter"/>.
 /// </summary>
 /// <param name="fileName">The file stream.</param>
 /// <param name="header">The header.</param>
 /// <param name="footer">The footer.</param>
 /// <param name="formatter">The formatter.</param>
 public FlatFileTraceListener(string fileName, string header = null, string footer = null, ILogFormatter formatter = null)
     : base(EnvironmentHelper.ReplaceEnvironmentVariables(fileName), formatter)
 {
     this.header = header ?? string.Empty;
     this.footer = footer ?? string.Empty;
 }