Bug 141951 Export data throw NPE when target document doesn't exist
Description: Export data doesn't work when deploy birt in WebSphere6 Steps to reproduce: 1. Deploy birt in WebSphere6 2. Preview report and click Export Data Result: java.lang.NullPointerException Stack Trace: org.apache.axis.AxisFault.makeFault(AxisFault.java:101) org.eclipse.birt.report.soapengine.processor.AbstractBaseComponentProcessor.process(Unknown Source) org.eclipse.birt.report.soapengine.endpoint.BirtSoapBindingImpl.getUpdatedObjects(Unknown Source) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/service/BirtViewerReportService.java
Object o = it.next( );
			if ( o instanceof ParameterGroupDefinition )
			{
				ParameterGroupDefinition group = (ParameterGroupDefinition) o;
				ret.addAll( group.getParameters( ) );
			}
			else
				ret.add( o );
		}
		return ret;
	}
	private static List convertParametersInGroup( Collection scalarParameters,
			ParameterGroupDefinition group, IGetParameterDefinitionTask task )
	{
		if ( scalarParameters == null )
			return null;
		List ret = new ArrayList( );
		for ( Iterator it = scalarParameters.iterator( ); it.hasNext( ); )
		{
			IScalarParameterDefn engineParam = (IScalarParameterDefn) it.next( );
			ParameterDefinition param = convertScalarParameter( engineParam,
					group, task );
			ret.add( param );
		}
		return ret;
	}
	private static ParameterGroupDefinition convertParameterGroup(
			IParameterGroupDefn engineParam, IGetParameterDefinitionTask task )
	{
		boolean cascade = engineParam instanceof ICascadingParameterGroup;