code: public StringColumn set(Selection rowSelection, String newValue) {
          for (int row : rowSelection) {
              set(row, newValue);
          }
          return this;
      }
docs: Conditionally update this column, replacing current values with newValue for all rows where the current value
  matches the selection criteria
  <p>
  Examples:
  myCatColumn.set(myCatColumn.isEqualTo("Cat"), "Dog"); // no more cats
  myCatColumn.set(myCatColumn.valueIsMissing(), "Fox"); // no more missing values