Bug 53201 NPE when re-running newly generated javadoc.xml
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javadocexport/JavadocOptionsManager.java
FileOutputStream objectStreamOutput= null;
		
		
		String antpath= fAntpath;
		try {
			if (antpath.length() > 0) {
				File file= new File(antpath);
				IPath antPath= new Path(antpath);
				IPath antDir= antPath.removeLastSegments(1);
				
				IPath basePath= null;
				IWorkspaceRoot root= ResourcesPlugin.getWorkspace().getRoot();
				if (root.findFilesForLocation(antPath).length > 0) {
					basePath= antDir; 
				}
				
				antDir.toFile().mkdirs();
			
				objectStreamOutput= new FileOutputStream(file);
				JavadocWriter writer= new JavadocWriter(objectStreamOutput, basePath, projects);
				writer.writeXML(this);
			}
		} catch (IOException e) {
			String message= JavadocExportMessages.getString("JavadocOptionsManager.createXM.error"); 
			throw new CoreException(JavaUIStatus.createError(IStatus.ERROR, message, e));
		} catch (ParserConfigurationException e) {
			String message= JavadocExportMessages.getString("JavadocOptionsManager.createXM.error"); 
			throw new CoreException(JavaUIStatus.createError(IStatus.ERROR, message, e));
		} catch (TransformerException e) {
			String message= JavadocExportMessages.getString("JavadocOptionsManager.createXM.error");