code: private static void setLegacy(String moduleName, String legacyParamName) {
          String oldValue = g_legacyToModuleMap.put(legacyParamName, moduleName);
          if (oldValue != null) {
              logger.warn("Legacy parameter name used twice: {}", legacyParamName);
          }
      }
docs: Register the given legacy parameter name as owned by the given module name.