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
*/
		EClass NUMBER_DATA_SET = eINSTANCE.getNumberDataSet( );
		/**
		 * The meta object literal for the '{@link org.eclipse.birt.chart.model.data.impl.OrthogonalSampleDataImpl <em>Orthogonal Sample Data</em>}' class.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @see org.eclipse.birt.chart.model.data.impl.OrthogonalSampleDataImpl
		 * @see org.eclipse.birt.chart.model.data.impl.DataPackageImpl#getOrthogonalSampleData()
		 * @generated
		 */
		EClass ORTHOGONAL_SAMPLE_DATA = eINSTANCE.getOrthogonalSampleData( );
		/**
		 * The meta object literal for the '<em><b>Data Set Representation</b></em>' attribute feature.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @generated
		 */
		EAttribute ORTHOGONAL_SAMPLE_DATA__DATA_SET_REPRESENTATION = eINSTANCE.getOrthogonalSampleData_DataSetRepresentation( );
		/**
		 * The meta object literal for the '<em><b>Series Definition Index</b></em>' attribute feature.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @generated
		 */
		EAttribute ORTHOGONAL_SAMPLE_DATA__SERIES_DEFINITION_INDEX = eINSTANCE.getOrthogonalSampleData_SeriesDefinitionIndex( );
		/**
		 * The meta object literal for the '{@link org.eclipse.birt.chart.model.data.impl.QueryImpl <em>Query</em>}' class.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @see org.eclipse.birt.chart.model.data.impl.QueryImpl