code: void logOrphans(final List<Map<String, Object>> toLog) {
          try {
              String result = pretty
                      ? prettyWriter().writeValueAsString(toLog)
                      : writer().writeValueAsString(toLog);
              LOGGER.warn("Orphan responses observed: {}", result);
          } catch (Exception ex) {
              LOGGER.warn("Could not write orphan log.", ex);
          }
      }
docs: This method is intended to be overridden in test implementations
  to assert against the output.