Bug 193875 we can not get an entir url by IHTMLActionHandler
we can not get an entir url by IHTMLActionHandler, so word emitter dose not write the right url. now hyperlink drill through in word emitter doesn't work.
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/utility/ParameterAccessor.java
if ( nullParams != null && nullParams.contains( name ) )
		{
			isExist = true;
		}
		return isExist;
	}
	/**
	 * If set isWorkingFolderAccessOnly as true, check the file if exist in
	 * working folder.
	 * 
	 * @param filePath
	 * @return boolean
	 */
	public static boolean isValidFilePath( String filePath )
	{
		if ( filePath == null )
			return false;
		if ( isWorkingFolderAccessOnly )
		{
			File docFile = new File( filePath );
			if ( !docFile.isAbsolute( ) )
			{
				if ( filePath.indexOf( ".." ) != -1 ) 
					return false;
				return true;
			}
			File docFolder = new File( workingFolder );
			if ( docFolder.isAbsolute( ) )
			{
				String absolutePath = docFile.getAbsolutePath( );