Bug 153412 Change parameter type will cause preview fail
Description: Change parameter type will cause preview fail Steps to reproduce: 1. New a report paramter, string, text-box, default value is abc. 2. Drag the parameter to Layout and preview. 3. Change the parameter's type to integer, list-box, add a value 1 4. Preview Expected result: No errors. Actual result: The value "abc" is invalid with the type "integer".
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/IBirtConstants.java
{
	
	static public final String OPRAND_PAGENO = "page"; 
	static public final String OPRAND_BOOKMARK = "bookmark"; 
	static public final String OPRAND_TOC = "isToc"; 
	static public final String OPRAND_SVG = "svg"; 
	static public final String OPRAND_PARAM = "param"; 
	static public final String OPRAND_IID = "iid"; 
	
	static public String MIME_TYPE = "text/xml"; 
	static public String HTML_RENDER_FORMAT = HTMLRenderOption.OUTPUT_FORMAT_HTML;
	public static final String PDF_RENDER_FORMAT = HTMLRenderOption.OUTPUT_FORMAT_PDF;
	
	public static final String SERVLET_PATH_PARAMETER = "/parameter"; 
	
	public static final String SERVLET_PATH_PREVIEW = "/preview"; 
	
	public static final String SERVLET_PATH_FRAMESET = "/frameset";