Bug 141950 Selection of select value in data set filter is error
Details: Selection of select value in data set filter is error Step: 1.New a report design. 2.Create a sample datasource and dataset. 3.Switch to filter. 4.Select a value in expression. 5.Drop the list of the value1 and select <select value...> Actual result: No value is appear and pop up an error. It said that "An expression has not been set"
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/data/ui/util/DataSetProvider.java
{
			
			IExtension ext = dataSourceElem.getDeclaringExtension( );
			IConfigurationElement[] elements = ext.getConfigurationElements( );
			for ( int n = 0; n < elements.length; n++ )
			{
				if ( elements[n].getAttribute( "id" ).equals( dataSetType ) ) 
				{
					return elements[n];
				}
			}
		}
		return null;
	}
	
	/**
	 * @param dataSourceType
	 * @return
	 */
	public static IConfigurationElement findDataSourceElement(
			String dataSourceType )
	{
		assert ( dataSourceType != null );
		
		IConfigurationElement element = (IConfigurationElement) htDataSourceExtensions.get( dataSourceType );
		if ( element == null )
		{
			IConfigurationElement[] elements = Platform.getExtensionRegistry( )
					.getConfigurationElementsFor( "org.eclipse.birt.report.designer.ui.odadatasource" ); 			for ( int n = 0; n < elements.length; n++ )
			{