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
		 */
		EAttribute RULE__TYPE = eINSTANCE.getRule_Type( );
		/**
		 * The meta object literal for the '<em><b>Value</b></em>' attribute feature.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @generated
		 */
		EAttribute RULE__VALUE = eINSTANCE.getRule_Value( );
		/**
		 * The meta object literal for the '{@link org.eclipse.birt.chart.model.data.impl.SampleDataImpl <em>Sample Data</em>}' class.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @see org.eclipse.birt.chart.model.data.impl.SampleDataImpl
		 * @see org.eclipse.birt.chart.model.data.impl.DataPackageImpl#getSampleData()
		 * @generated
		 */
		EClass SAMPLE_DATA = eINSTANCE.getSampleData( );
		/**
		 * The meta object literal for the '<em><b>Base Sample Data</b></em>' containment reference list feature.
		 * <!-- begin-user-doc -->
		 * <!-- end-user-doc -->
		 * @generated
		 */
		EReference SAMPLE_DATA__BASE_SAMPLE_DATA = eINSTANCE.getSampleData_BaseSampleData( );
		/**
		 * The meta object literal for the '<em><b>Orthogonal Sample Data</b></em>' containment reference list feature.
		 * <!-- begin-user-doc -->