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
* 
	 * @param s
	 *            string to be encoded.
	 * @param format
	 *            encoding format.
	 * @return
	 */
	protected static String urlEncode( String s, String format )
	{
		assert ISO_8859_1_ENCODE.equalsIgnoreCase( format )
				|| UTF_8_ENCODE.equalsIgnoreCase( format );
		String encodedString = s;
		if ( s != null )
		{
			try
			{
				encodedString = URLEncoder.encode( s, format );
			}
			catch ( UnsupportedEncodingException e )
			{
				encodedString = s;
			}
		}
		return encodedString;
	}
	/**
	 * Parse config file name from report design filename.
	 * 
	 * @param reportDesignName
	 *            String