code: @Override
      public JavaShellToolBuilder persistence(Map<String, String> prefsMap) {
          this.prefs = new MapStorage(prefsMap);
          return this;
      }
docs: Set the storage mechanism for persistent information which includes
  input history and retained settings.   Default if not set is the
  tool's standard persistence mechanism.
  
  @param prefsMap  an instance of {@link java.util.Map} that
  is used to retrieve and store persistent information
  @return the {@code JavaShellToolBuilder} instance