code: public FormInputHandler dataSet(final DataSet theDataSet) {
  		checkState(dataSet == null, "Cannot specify a DataSet because a direct value is already set.");
  
  		Fields fields = new Fields(this);
  		fields.dataSet = theDataSet;
  		return new FormInputHandler(fields);
  	}
docs: Creates a new {@link FormInputHandler} based on this {@link FormInputHandler} using the specified {@link DataSet} to
  retrieve values from.
  
  @param theDataSet
  the {@link DataSet} to retrieve the value from
  @return the new {@link FormInputHandler} instance