Bug 155496 Due to inactivity, a group report gives NULL Pointer Exception on selection of TOC and Export CSV option
Steps to reproduce this issue:- 1. Access any Group report that lists groups in TOC 2. For some time do not do any activity on report page (say 15 mins.) 3. Now click on Toggle Table Contents Link 4. The pop window gets opened with following error message java.lang.NullPointerException org.apache.axis.AxisFault.makeFault(AxisFault.java:101) org.eclipse.birt.report.soapengine.processor.AbstractBaseComponentProcessor.process(Unknown Source) org.eclipse.birt.report.soapengine.endpoint.BirtSoapBindingImpl.getUpdatedObjects(Unknown Source) sun.reflect.GeneratedMethodAccessor80.invoke(Unknown Source) When page remains idle for some time the same error gets displayed on selection of Export CSV option. Note:- This issue occurs for the reports that are run using '__overwrite' option. Any help on this is highly appreciated.
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/utility/ParameterAccessor.java
* folder. So if a report file path is relative path, it's absolute path is
	 * synthesized by appending file path to the document folder path.
	 * 
	 * @param file
	 * @return
	 */
	protected static String createAbsolutePath( String filePath )
	{
		if ( isRelativePath( filePath ) )
		{
			return documentFolder + File.separator + filePath;
		}
		return filePath;
	}
	/**
	 * If set isDocumentFolderAccessOnly as true, check the file if exist in
	 * document folder.
	 * 
	 * @param filePath
	 * @return boolean
	 */
	public static boolean isValidFilePath( String filePath )
	{
		assert filePath != null;
		if ( isDocumentFolderAccessOnly )
		{
			String absolutePath = new File( filePath ).getAbsolutePath( );
			String docFolderPath = new File( documentFolder ).getAbsolutePath( );
			
			if ( isWindowsPlatform( ) )