code: @Override
      public DataSource lookupDataSource(String dataSourceName) {
  
          try {
              final Context context = contextInstance.get();
              if (context == null) {
                  throw new ContextNotAvailableException("No Naming Context available.");
              }
              return (DataSource) context.lookup(dataSourceName);
          } catch (NamingException e) {
              throw new DataSourceNotFoundException("Unable to find data source for given name: " + dataSourceName, e);
          }
      }
docs: {@inheritDoc}