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 SERIES_DEFINITION__SERIES_PALETTE = eINSTANCE.getSeriesDefinition_SeriesPalette( );
		/**
		 * The meta object literal for the '<em><b>Series Definitions</b></em>' containment reference list feature.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @generated
		 */
		EReference SERIES_DEFINITION__SERIES_DEFINITIONS = eINSTANCE.getSeriesDefinition_SeriesDefinitions( );
		/**
		 * The meta object literal for the '<em><b>Format Specifier</b></em>' containment reference feature.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @generated
		 */
		EReference SERIES_DEFINITION__FORMAT_SPECIFIER = eINSTANCE.getSeriesDefinition_FormatSpecifier( );
		/**
		 * The meta object literal for the '<em><b>Series</b></em>' containment reference list feature.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @generated
		 */
		EReference SERIES_DEFINITION__SERIES = eINSTANCE.getSeriesDefinition_Series( );
		/**
		 * The meta object literal for the '<em><b>Grouping</b></em>' containment reference feature.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @generated