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
SERIES_DEFINITION__SERIES_DEFINITIONS );
		createEReference( seriesDefinitionEClass,
				SERIES_DEFINITION__FORMAT_SPECIFIER );
		createEReference( seriesDefinitionEClass, SERIES_DEFINITION__SERIES );
		createEReference( seriesDefinitionEClass, SERIES_DEFINITION__GROUPING );
		createEAttribute( seriesDefinitionEClass, SERIES_DEFINITION__SORTING );
		seriesGroupingEClass = createEClass( SERIES_GROUPING );
		createEAttribute( seriesGroupingEClass, SERIES_GROUPING__ENABLED );
		createEAttribute( seriesGroupingEClass, SERIES_GROUPING__GROUPING_UNIT );
		createEReference( seriesGroupingEClass,
				SERIES_GROUPING__GROUPING_ORIGIN );
		createEAttribute( seriesGroupingEClass,
				SERIES_GROUPING__GROUPING_INTERVAL );
		createEAttribute( seriesGroupingEClass, SERIES_GROUPING__GROUP_TYPE );
		createEAttribute( seriesGroupingEClass,
				SERIES_GROUPING__AGGREGATE_EXPRESSION );
		stockDataSetEClass = createEClass( STOCK_DATA_SET );
		textDataSetEClass = createEClass( TEXT_DATA_SET );
		triggerEClass = createEClass( TRIGGER );
		createEAttribute( triggerEClass, TRIGGER__CONDITION );
		createEReference( triggerEClass, TRIGGER__ACTION );
		createEAttribute( triggerEClass, TRIGGER__TRIGGER_FLOW );
		
		dataEDataType = createEDataType( DATA );
	}
	/**
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 */
	private boolean isInitialized = false;