Bug 147407 Preview the attached report in the web viewer first time and then click the TOC button will cause NPE error
Description: It just can be reprouduced at first time preview. Step to reproduce: 1. please use attach report file 2. preview it in the web viewer 3. click the "Toggle table of contents" button Actual result: As the atteched screenshot shows,There is a NPE error.And if you preview it in the Web viewer again, the phenomenon is disappear.But reopen the eclipse and preview it at first time, it will be occured.
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/utility/ParameterAccessor.java
* @return parameter value
	 */
	public static String getReportParameter( HttpServletRequest request,
			String name, String defaultValue )
	{
		assert request != null && name != null;
		String value = getParameter( request, name );
		if ( value == null || ( (String) value ).trim( ).length( ) <= 0 ) 
		
		{
			value = ""; 
		}
		Map paramMap = request.getParameterMap( );
		String ISOName = toISOString( name );
		if ( paramMap == null || !paramMap.containsKey( ISOName ) )
		{
			value = defaultValue;
		}
		Set nullParams = getParameterValues( request, PARAM_ISNULL );
		if ( nullParams != null && nullParams.contains( name ) )
		{
			value = null;
		}
		return value;
	}
	/**
	 * Get result set name.
	 * 
	 * @param request
	 * @return