code: public RegularFile getOrCreateRegularFile(
        JimfsPath path, Set<OpenOption> options, FileAttribute<?>... attrs) throws IOException {
      checkNotNull(path);
  
      if (!options.contains(CREATE_NEW)) {
        // assume file exists unless we're explicitly trying to create a new file
        RegularFile file = lookUpRegularFile(path, options);
        if (file != null) {
          return file;
        }
      }
  
      if (options.contains(CREATE) || options.contains(CREATE_NEW)) {
        return getOrCreateRegularFileWithWriteLock(path, options, attrs);
      } else {
        throw new NoSuchFileException(path.toString());
      }
    }
docs: Gets the regular file at the given path, creating it if it doesn't exist and the given options
  specify that it should be created.