Bug 168172 Add the get() and set() functions of HideDetail parameter on IGroup
Add the get() and set() functions of HideDetail parameter on IGroup, and thus enable the hidedetail shifting on the Group through eventhandler.
engine/org.eclipse.birt.report.engine.tests/test/org/eclipse/birt/report/engine/api/script/element/ElementTest.java
* @throws ScriptException
	 */
	public void testHideRule( ) throws SemanticException, ScriptException
	{
		TableHandle tableHandle = factory.newTableItem( "table", 3 );
		designHandle.getBody( ).add( tableHandle );
		HideRule hide = StructureFactory.createHideRule( );
		hide.setFormat( "format" );
		HideRuleHandle hideHandle = (HideRuleHandle) tableHandle
				.getPropertyHandle( "visibility" ).addItem( hide );
		HideRule hide2 = StructureFactory.createHideRule( );
		hide2.setExpression( "expr2" );
		hide2.setFormat( "format" );
		tableHandle.getPropertyHandle( "visibility" ).addItem( hide2 );
		IReportItem item = new ReportItem( tableHandle );
		IHideRule[] rules = item.getHideRules( );
		assertEquals( 2, rules.length );
		IHideRule iHide = new HideRuleImpl( hideHandle );
		assertEquals( "format", iHide.getFormat( ) ); 
		iHide.setValueExpr( "valueExpr" ); 
		assertEquals( "valueExpr", iHide.getValueExpr( ) ); 
		item.removeHideRule( iHide );
		rules = item.getHideRules( );
		assertEquals( 1, rules.length );
	}
	public void testDataSet( ) throws ScriptException
	{
		DataSetHandle dataSetHandle = factory.newOdaDataSet( "DataSet", null );
		IDataSet dataSet = new DataSet( dataSetHandle );
		dataSet.setPrivateDriverProperty( KEY, VALUE );