private List<Replace> getAllowedReplacements(Cluster cluster, String configType, List<Replace> replacements){
    List<Replace> allowedReplacements= new ArrayList<>();

    for(Replace replacement: replacements){
      if(isOperationAllowed(cluster, configType, replacement.key, replacement)) {
        allowedReplacements.add(replacement);
      }
    }

    return allowedReplacements;
  }
Finds the values that should be preserved during a delete. This includes:
<ul>
<li>Properties that existed on the stack but were changed to a different
value</li>
<li>Properties that do not exist on the stack</li>
</ul>

@param clusterName
         the cluster name
@param config
         the config with the tag to find conflicts
@return the list of changed property keys
@throws AmbariException
ambari-server/src/main/java/org/apache/ambari/server/serveraction/upgrades/ConfigureAction.java