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
* <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for the attribute '<em>Group Type</em>'.
	 * @see org.eclipse.birt.chart.model.data.SeriesGrouping#getGroupType()
	 * @see #getSeriesGrouping()
	 * @generated
	 */
	EAttribute getSeriesGrouping_GroupType( );
	/**
	 * Returns the meta object for the attribute '{@link org.eclipse.birt.chart.model.data.SeriesGrouping#getAggregateExpression <em>Aggregate Expression</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for the attribute '<em>Aggregate Expression</em>'.
	 * @see org.eclipse.birt.chart.model.data.SeriesGrouping#getAggregateExpression()
	 * @see #getSeriesGrouping()
	 * @generated
	 */
	EAttribute getSeriesGrouping_AggregateExpression( );
	/**
	 * Returns the meta object for class '{@link org.eclipse.birt.chart.model.data.StockDataSet <em>Stock Data Set</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for class '<em>Stock Data Set</em>'.
	 * @see org.eclipse.birt.chart.model.data.StockDataSet
	 * @generated
	 */
	EClass getStockDataSet( );
	/**
	 * Returns the meta object for class '{@link org.eclipse.birt.chart.model.data.TextDataSet <em>Text Data Set</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for class '<em>Text Data Set</em>'.
	 * @see org.eclipse.birt.chart.model.data.TextDataSet
	 * @generated