docs: static void merge(Map<ConfigurationKey, Object> original, Map<ConfigurationKey, Object> toMerge, String mergedSourceDescription) {
          for (Entry<ConfigurationKey, Object> entry : toMerge.entrySet()) {
              Object existing = original.get(entry.getKey());
              if (existing != null) {
                  ConfigurationLogger.LOG.configurationKeyAlreadySet(entry.getKey().get(), existing, entry.getValue(), mergedSourceDescription);
              } else {
                  original.put(entry.getKey(), entry.getValue());
              }
          }
      }