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
* <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 */
	public BaseSampleData createBaseSampleData( )
	{
		BaseSampleDataImpl baseSampleData = new BaseSampleDataImpl( );
		return baseSampleData;
	}
	/**
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 */
	public BubbleDataSet createBubbleDataSet( )
	{
		BubbleDataSetImpl bubbleDataSet = new BubbleDataSetImpl( );
		return bubbleDataSet;
	}
	/**
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 */
	public DataElement createDataElement( )
	{
		DataElementImpl dataElement = new DataElementImpl( );
		return dataElement;
	}
	/**
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated