code: public void indexSourceTree(final Folder rootFolder) {
  
  		logger.info("Starting indexing of source tree " + rootFolder.getPath());
  
  		final SecurityContext securityContext = rootFolder.getSecurityContext();
  		app = StructrApp.getInstance(securityContext);
  
  		structrTypeSolver.parseRoot(rootFolder);
  
  		final CombinedTypeSolver typeSolver = new CombinedTypeSolver();
  		typeSolver.add(new ReflectionTypeSolver());
  		typeSolver.add(structrTypeSolver);
  
  		facade = JavaParserFacade.get(typeSolver);
  
  		logger.info("Done with indexing of source tree " + rootFolder.getPath());
  	}
docs: Create an index containing all compilation units of Java files from
  the source tree under the given root folder.
  
  @param rootFolder