private void doMergeInfo(
            FileGroup fileGroupToMergeInto,
            FileGroup fileGroupToMerge)
        {
            var dataDst  = new DataProcessing(fileGroupToMergeInto);
            var tableDst = dataDst.GetDataTableFromResxFiles(_project);

            var dataSrc  = new DataProcessing(fileGroupToMerge);
            var tableSrc = dataSrc.GetDataTableFromResxFiles(_project);

            // Jede ID muss eindeutig sein.
            checkUniqueIDs(fileGroupToMergeInto, fileGroupToMerge, tableDst, tableSrc);

            // http://stackoverflow.com/a/16617567/107625
            tableDst.Merge(tableSrc);

            // Checksums übernehmen.
            var dstChecksum = fileGroupToMergeInto.GetChecksum(_project);

            foreach (DataRow row in tableDst.Rows)
            {
                row[0] = dstChecksum;
            }

            // Write back.
            dataDst.SaveDataTableToResxFiles(_project, tableDst, false, false);
        }