Bug 188052 Enhance the behavior of DimensionConditionHandle
Current in model implementation, there could be multiple DimensionConditionHandle corresponding to one dimension. This will cause problem for both UI and DtE. What we expect is that for each dimension, there are only one DimensionConditionHandle accompany with. Model should merge all the duplicate DimensionConditionHandle so that when UI/DtE is using model API the we can get unique DimensionConditionHandle for each dimension.
model/org.eclipse.birt.report.model.tests/test/org/eclipse/birt/report/model/parser/TabularCubeParserTest.java
assertTrue( compareFile( "TabularCubeParserTest_extends_golden_1.xml" ) ); 
		AccessControlHandle control = designHandle.getElementFactory( )
				.newAccessControl( );
		control.addUserName( "new user name 1" ); 
		newCube.add( ICubeModel.ACCESS_CONTROLS_PROP, control );
		save( );
		assertTrue( compareFile( "TabularCubeParserTest_extends_golden_2.xml" ) ); 
		designHandle.getCommandStack( ).undo( );
		LevelHandle level = designHandle.findLevel( "testDimension1/testLevel" ); 
		ValueAccessControlHandle valueAccess = designHandle.getElementFactory( )
				.newValueAccessControl( );
		valueAccess.addValue( "new value 1" ); 
		level.add( ILevelModel.VALUE_ACCESS_CONTROLS_PROP, valueAccess );
		save( );
		assertTrue( compareFile( "TabularCubeParserTest_extends_golden_3.xml" ) ); 
		valueAccess
				.setPermission( DesignChoiceConstants.ACCESS_PERMISSION_ALLOW );
	}
	/**
	 * Notification should be only sent to cube if access control/value access
	 * controls are changed. It should be only one PROPERTY event.
	 * 
	 * <ul>
	 * <li>for local value change.
	 * <li>for extends case.
	 * </ul>
	 * 
	 * @throws Exception
	 */
	public void testNotification( ) throws Exception