code: private static boolean isValidVersionString(String version) {
      /*
       * Git version strings can vary, so let's do a minimal sanity check for two things: 1. The first
       * character in the version is a number. 2. There's at least one period in the version string.
       * 
       * TODO (rs2705): Make this more sophisticated by parsing out a major/minor version number, and
       * ensuring it's >= some minimally-required version.
       */
      try {
        Integer.parseInt(version.substring(0, 1));
      } catch (NumberFormatException e) {
        // First character in the version string was not a valid number!
        return false;
      }
  
      if (version.indexOf(".") == -1) {
        // The version string doesn't contain a period!
        return false;
      }
  
      return true;
    }
docs: Judge the validity of a given git version string. This can be difficult to do, as there seems
  to be no deliberately-defined git version format. So, here we do a minimal sanity check for two
  things: 1. The first character in the version is a number. 2. There's at least one period in
  the version string.
  
  @param version
  @return true if the version passed as argument is valid