code: public FormInputHandler dataKeyWithIndex(final String theDataKey, final Integer theDataIndex) {
  		checkState(dataSet != null, "Cannot specify a data key. Please specify a DataSet first.");
  
  		Fields fields = new Fields(this);
  		fields.dataKey = theDataKey;
  		fields.dataIndex = theDataIndex;
  		return new FormInputHandler(fields);
  	}
docs: Creates a new {@link FormInputHandler} based on this {@link FormInputHandler} using the specified data key and the
  specified index for retrieving the value from the {@link DataSet} associated with this {@link FormInputHandler}.
  
  @param theDataKey
  the data set key used to retrieve the value from the specified data set
  @param theDataIndex
  the index for retrieving the value from the specified data set
  @return the new {@link FormInputHandler} instance