public Configuration copy() {
    Configuration parent = parentConfiguration;
    parentConfiguration = null;
    Configuration copy = new Configuration(getFullProperties(), getFullAttributes());
    parentConfiguration = parent;
    return copy;
  }
Returns true if the property exists in clusterConfigProperties and has a custom user defined value. Property has
custom value in case we there's no stack default value for it or it's not equal to stack default value.
ambari-server/src/main/java/org/apache/ambari/server/topology/Configuration.java