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 -->
	 * @see org.eclipse.birt.chart.model.data.impl.NumberDataSetImpl
	 * @see org.eclipse.birt.chart.model.data.impl.DataPackageImpl#getNumberDataSet()
	 * @generated
	 */
	int NUMBER_DATA_SET = 10;
	/**
	 * The feature id for the '<em><b>Values</b></em>' attribute. <!--
	 * begin-user-doc --> <!-- end-user-doc -->
	 * 
	 * @generated
	 * @ordered
	 */
	int NUMBER_DATA_SET__VALUES = DATA_SET__VALUES;
	/**
	 * The number of structural features of the '<em>Number Data Set</em>' class.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 * @ordered
	 */
	int NUMBER_DATA_SET_FEATURE_COUNT = DATA_SET_FEATURE_COUNT + 0;
	/**
	 * The meta object id 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
	 */
	int ORTHOGONAL_SAMPLE_DATA = 11;
	/**