code: public DBService getDefaultDB() {
          String defaultTenantName = TenantService.instance().getDefaultTenantName();
          synchronized (m_tenantDBMap) {
              DBService dbservice = m_tenantDBMap.get(defaultTenantName);
              assert dbservice != null : "Database for default tenant not found";
              return dbservice;
          }
      }
docs: Get the DBService for the default database. This object is created when the
  DBManagerService is started.
  
  @return {@link DBService} for the defaultdatabase.