code: public static Key toKey(RowColumn rc) {
      if ((rc == null) || (rc.getRow().equals(Bytes.EMPTY))) {
        return null;
      }
      Text row = ByteUtil.toText(rc.getRow());
      if ((rc.getColumn().equals(Column.EMPTY)) || !rc.getColumn().isFamilySet()) {
        return new Key(row);
      }
      Text cf = ByteUtil.toText(rc.getColumn().getFamily());
      if (!rc.getColumn().isQualifierSet()) {
        return new Key(row, cf);
      }
      Text cq = ByteUtil.toText(rc.getColumn().getQualifier());
      if (!rc.getColumn().isVisibilitySet()) {
        return new Key(row, cf, cq);
      }
      Text cv = ByteUtil.toText(rc.getColumn().getVisibility());
      return new Key(row, cf, cq, cv);
    }
docs: Converts from a Fluo RowColumn to a Accumulo Key
  
  @param rc RowColumn
  @return Key