docs: function getDimCount(source, sysDims, dimsDef, optDimCount) {
      // Note that the result dimCount should not small than columns count
      // of data, otherwise `dataDimNameMap` checking will be incorrect.
      var dimCount = Math.max(
          source.dimensionsDetectCount || 1,
          sysDims.length,
          dimsDef.length,
          optDimCount || 0
      );
      each(sysDims, function (sysDimItem) {
          var sysDimItemDimsDef = sysDimItem.dimsDef;
          sysDimItemDimsDef && (dimCount = Math.max(dimCount, sysDimItemDimsDef.length));
      });
      return dimCount;
  }