code: public void setStyleNames (int row, int column, String... styles)
      {
          int idx = 0;
          for (String style : styles) {
              if (idx++ == 0) {
                  getFlexCellFormatter().setStyleName(row, column, style);
              } else {
                  getFlexCellFormatter().addStyleName(row, column, style);
              }
          }
      }
docs: Configures the specified style names on the specified row and column. The first style is set
  as the primary style and additional styles are added onto that.