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
EAttribute getSeriesGrouping_Enabled( );
	/**
	 * Returns the meta object for the attribute '{@link org.eclipse.birt.chart.model.data.SeriesGrouping#getGroupingUnit <em>Grouping Unit</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for the attribute '<em>Grouping Unit</em>'.
	 * @see org.eclipse.birt.chart.model.data.SeriesGrouping#getGroupingUnit()
	 * @see #getSeriesGrouping()
	 * @generated
	 */
	EAttribute getSeriesGrouping_GroupingUnit( );
	/**
	 * Returns the meta object for the containment reference '{@link org.eclipse.birt.chart.model.data.SeriesGrouping#getGroupingOrigin <em>Grouping Origin</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for the containment reference '<em>Grouping Origin</em>'.
	 * @see org.eclipse.birt.chart.model.data.SeriesGrouping#getGroupingOrigin()
	 * @see #getSeriesGrouping()
	 * @generated
	 */
	EReference getSeriesGrouping_GroupingOrigin( );
	/**
	 * Returns the meta object for the attribute '{@link org.eclipse.birt.chart.model.data.SeriesGrouping#getGroupingInterval <em>Grouping Interval</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for the attribute '<em>Grouping Interval</em>'.
	 * @see org.eclipse.birt.chart.model.data.SeriesGrouping#getGroupingInterval()
	 * @see #getSeriesGrouping()
	 * @generated
	 */
	EAttribute getSeriesGrouping_GroupingInterval( );
	/**
	 * Returns the meta object for the attribute '{@link org.eclipse.birt.chart.model.data.SeriesGrouping#getGroupType <em>Group Type</em>}'.