code: public static Connection getDefaultConnection(ServerConfiguration serverConfig) {
          ModuleConfiguration poolConfig =
                  serverConfig
                          .getModuleConfiguration("org.fcrepo.server.storage.ConnectionPoolManager");
          String datastoreID =
                  poolConfig.getParameter("defaultPoolName",Parameter.class).getValue();
          DatastoreConfiguration dbConfig =
                  serverConfig.getDatastoreConfiguration(datastoreID);
          return getConnection(dbConfig.getParameter("jdbcDriverClass",Parameter.class)
                                       .getValue(),
                               dbConfig.getParameter("jdbcURL",Parameter.class).getValue(),
                               dbConfig.getParameter("dbUsername",Parameter.class).getValue(),
                               dbConfig.getParameter("dbPassword",Parameter.class).getValue());
      }
docs: Gets a connection to the database specified in connection pool module's
  "defaultPoolName" config value. This allows us to the connect to the
  database without the server running.