NLog.Targets.FileTarget.WriteHeader C# (CSharp) Method

        private void WriteHeader(BaseFileAppender appender)
        {
            //performance: cheap check before checking file info 
            if (Header == null) return;

            //todo replace with hasWritten?
            var length = appender.GetFileLength();
            //  Write header only on empty files or if file info cannot be obtained.
            if (length == null || length == 0)
            {
                byte[] headerBytes = this.GetHeaderBytes();
                if (headerBytes != null)
                {
                    appender.Write(headerBytes);
                }
            }
        }