Bug 156335 Blank value is not accepted without display text
Steps to reproduce: 1.New a list parameter, add a seletion choice: value->blank, display text->a 2.Drag the parameter to the layout 3.Preview, choose "a" in select list, blank value is accepted. It's expected result 4.Back to the layout, clean the display text for the parameter 5.Preview, choose the blank value in select list Expected result: Blank value is accepted Actual result: "Parameter should have a value"
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/service/actionhandler/BirtCacheParameterActionHandler.java
/*************************************************************************************
 * Copyright (c) 2004 Actuate Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     Actuate Corporation - Initial implementation.
 ************************************************************************************/
package org.eclipse.birt.report.service.actionhandler;
import java.io.File;
import org.eclipse.birt.report.IBirtConstants;
import org.eclipse.birt.report.context.IContext;
import org.eclipse.birt.report.context.ViewerAttributeBean;
import org.eclipse.birt.report.model.api.DesignEngine;
import org.eclipse.birt.report.model.api.ReportDesignHandle;
import org.eclipse.birt.report.model.api.ScalarParameterHandle;
import org.eclipse.birt.report.model.api.SessionHandle;
import org.eclipse.birt.report.model.api.elements.DesignChoiceConstants;
import org.eclipse.birt.report.model.api.elements.structures.ConfigVariable;
import org.eclipse.birt.report.model.api.util.ParameterValidationUtil;
import org.eclipse.birt.report.service.api.IViewerReportService;
import org.eclipse.birt.report.soapengine.api.Data;
import org.eclipse.birt.report.soapengine.api.GetUpdatedObjectsResponse;
import org.eclipse.birt.report.soapengine.api.Operation;
import org.eclipse.birt.report.soapengine.api.Oprand;
import org.eclipse.birt.report.soapengine.api.Update;
import org.eclipse.birt.report.soapengine.api.UpdateData;
import org.eclipse.birt.report.utility.ParameterAccessor;