code: public static final String getGroup(Path file) throws IOException
      {
          if (supports("posix"))
          {
              PosixFileAttributeView view = Files.getFileAttributeView(file, PosixFileAttributeView.class);
              PosixFileAttributes attrs = view.readAttributes();
              GroupPrincipal group = attrs.group();
              return group.getName();
          }
          else
          {
              JavaLogging.getLogger(PosixHelp.class).warning("no posix support. getGroup(%s) returns \"\"", file);
              return "";
          }
      }
docs: Return linux file group name. Or ""
  @param file
  @return
  @throws IOException