code: public static ExternalSessionKey fromWebDriverRequest(String path) {
        int sessionIndex = path.indexOf("/session/");
        if (sessionIndex != -1) {
          sessionIndex += "/session/".length();
          int nextSlash = path.indexOf("/", sessionIndex);
          String session;
          if (nextSlash != -1) {
            session = path.substring(sessionIndex, nextSlash);
          } else {
            session = path.substring(sessionIndex, path.length());
          }
          if ("".equals(session)) {
            return null;
          }
          return new ExternalSessionKey(session);
        }
        return null;
    }
docs: extract the session xxx from http://host:port/a/b/c/session/xxx/...
  
  @param path The path to the session
  @return the ExternalSessionKey provided by the remote., or null if the url didn't contain a session id