private void applyAdditionalParameters(StageWrapper wrapper, Map<String, String> commandParams) {
    if (wrapper.getParams() != null) {
      for (Map.Entry<String, String> pair : wrapper.getParams().entrySet()) {
        if (!commandParams.containsKey(pair.getKey())) {
          commandParams.put(pair.getKey(), pair.getValue());
        }
      }
    }
  }
Modify the commandParams by applying additional parameters from the stage.
@param wrapper Stage Wrapper that may contain additional parameters.
@param commandParams Parameters to modify.
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/UpgradeResourceProvider.java