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
* Returns the meta object for class '
	 * {@link org.eclipse.birt.chart.model.data.Rule <em>Rule</em>}'. <!--
	 * begin-user-doc --> <!-- end-user-doc -->
	 * 
	 * @return the meta object for class '<em>Rule</em>'.
	 * @see org.eclipse.birt.chart.model.data.Rule
	 * @generated
	 */
	EClass getRule( );
	/**
	 * Returns the meta object for the attribute '{@link org.eclipse.birt.chart.model.data.Rule#getType <em>Type</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for the attribute '<em>Type</em>'.
	 * @see org.eclipse.birt.chart.model.data.Rule#getType()
	 * @see #getRule()
	 * @generated
	 */
	EAttribute getRule_Type( );
	/**
	 * Returns the meta object for the attribute '{@link org.eclipse.birt.chart.model.data.Rule#getValue <em>Value</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the meta object for the attribute '<em>Value</em>'.
	 * @see org.eclipse.birt.chart.model.data.Rule#getValue()
	 * @see #getRule()
	 * @generated
	 */
	EAttribute getRule_Value( );
	/**
	 * Returns the meta object for class '{@link org.eclipse.birt.chart.model.data.SampleData <em>Sample Data</em>}'.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->