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/DataPackageImpl.java
*/
	private EClass baseSampleDataEClass = null;
	/**
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 */
	private EClass bubbleDataSetEClass = null;
	/**
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 */
	private EClass dataElementEClass = null;
	/**
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 */
	private EClass dataSetEClass = null;
	/**
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 */
	private EClass dateTimeDataElementEClass = null;
	/**
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 */
	private EClass dateTimeDataSetEClass = null;
	/**
	 * <!-- begin-user-doc -->