code: public static StorageExt getSessionStorage() {
      if (sessionStorage == null && Storage.isSessionStorageSupported()) {
        sessionStorage = new StorageExt(Storage.getSessionStorageIfSupported());
      }
      return sessionStorage;
    }
docs: Returns a Session Storage.
  
  @return the sessionStorage instance, or <code>null</code> if Web Storage is NOT supported.