Jobs: add check for file age

Jobs/ZUGFeRD/ImportZUGFeRDFiles.vb

@@ -162,6 +162,11 @@ Public Class ImportZUGFeRDFiles
 
                 _logger.Info("Start processing file group {0}", oMessageId)
 
+                If _file.CheckFileAge(oFileGroupFiles, oArgs.MinFileAgeInMinutes) Then
+                    _logger.Info("At least one file was created less than [{0}] minutes ago. Skipping file group.")
+                    Continue For
+                End If
+
                 Dim oEmailDataBase = _email.GetEmailDataForMessageId(oMessageId)
 
                 Try