code: public static TransformedInputRow of(final InputRow row) {
          if (row instanceof TransformedInputRow) {
              // re-use existing transformed input row.
              return (TransformedInputRow) row;
          } else {
              return new TransformedInputRow(row, row.getId());
          }
      }
docs: Constructs a {@link TransformedInputRow} based on another row, or returns
  the row if it is already a {@link TransformedInputRow}.
  
  @param row
  @return