Bug 202254 Exception is thrown when category values are null and type of X axis is set to DateTime
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/model/data/impl/DataFactoryImpl.java
*/
	public DataSet createDataSet( )
	{
		DataSetImpl dataSet = new DataSetImpl( );
		return dataSet;
	}
	/**
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 */
	public DateTimeDataElement createDateTimeDataElement( )
	{
		DateTimeDataElementImpl dateTimeDataElement = new DateTimeDataElementImpl( );
		return dateTimeDataElement;
	}
	/**
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 */
	public DateTimeDataSet createDateTimeDataSet( )
	{
		DateTimeDataSetImpl dateTimeDataSet = new DateTimeDataSetImpl( );
		return dateTimeDataSet;
	}
	/**
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 */
	public DifferenceDataSet createDifferenceDataSet( )