code: protected void handleException(final Exception e) {
          if (_swallowException) {
              _logger.warn("Metrics collection failed.", e);
          } else {
              if (e instanceof RuntimeException) {
                  throw (RuntimeException) e;
              } else {
                  throw new RuntimeException(e);
              }
          }
      }
docs: Handles exceptions either by logging and swalling or by rethrowing as
  {@code RuntimeException} depending on the value of {@code _swallowException}.
  
  @param e An instance of <code>Exception</code>.