Bug 211710 [Regression] Data of cascading parameters in the report extended from the library can not be selected from the drop-down list when preview [01]
Description: Data of cascading parameters in the report extended from the library can not be selected from the drop-down list when preview. Build number: 2.2.2.v20071203-0630 Steps to reproduce: 1. New a Library with cascading parameters. 2. New a report and extend the cascading parameters from the library and preview. Expected result: Values can be selected from the drop-down list. Actual result: Values can not be selected from the drop-down list. Error log: N/A
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/GetParameterDefinitionTask.java
return cache.getRoot( );
	}
	private ParameterHelper[] getParameterHelpers(
			CascadingParameterGroupHandle parameterGroup )
	{
		SlotHandle parameters = parameterGroup.getParameters( );
		int parameterCount = parameters.getCount( );
		ParameterHelper[] parameterHelpers = new ParameterHelper[parameterCount];
		for ( int i = 0; i < parameterCount; i++ )
		{
			ScalarParameterHandle parameter = (ScalarParameterHandle) parameters.get( i );
			parameterHelpers[i] = new ParameterHelper( parameter, locale );
		}
		return parameterHelpers;
	}
	
	private Collection getChoicesFromParameterGroup(
			ScalarParameterHandle parameter, Object[] groupKeyValues )
	{
		assert isCascadingParameter( parameter );
		CascadingParameterGroupHandle parameterGroup = getCascadingGroup( parameter );
		IResultIterator iterator = getResultSetOfCascadingGroup( parameterGroup );
		if ( iterator == null )
		{
			return Collections.EMPTY_LIST;
		}
		return populateToList( iterator, parameter, new ParameterGroupFilter(
				groupKeyValues, parameterGroup ) );
	}
	private interface SelectionFilter