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/DataPackage.java
* <!-- end-user-doc -->
		 * @generated
		 */
		EReference ACTION__VALUE = eINSTANCE.getAction_Value( );
		/**
		 * The meta object literal for the '{@link org.eclipse.birt.chart.model.data.impl.BaseSampleDataImpl <em>Base Sample Data</em>}' class.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @see org.eclipse.birt.chart.model.data.impl.BaseSampleDataImpl
		 * @see org.eclipse.birt.chart.model.data.impl.DataPackageImpl#getBaseSampleData()
		 * @generated
		 */
		EClass BASE_SAMPLE_DATA = eINSTANCE.getBaseSampleData( );
		/**
		 * The meta object literal for the '<em><b>Data Set Representation</b></em>' attribute feature.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @generated
		 */
		EAttribute BASE_SAMPLE_DATA__DATA_SET_REPRESENTATION = eINSTANCE.getBaseSampleData_DataSetRepresentation( );
		/**
		 * The meta object literal for the '{@link org.eclipse.birt.chart.model.data.impl.BubbleDataSetImpl <em>Bubble Data Set</em>}' class.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @see org.eclipse.birt.chart.model.data.impl.BubbleDataSetImpl
		 * @see org.eclipse.birt.chart.model.data.impl.DataPackageImpl#getBubbleDataSet()
		 * @generated
		 */
		EClass BUBBLE_DATA_SET = eINSTANCE.getBubbleDataSet( );
		/**