public Class<? extends HostGroupStrategy> getAddServiceHostGroupStrategyClass() throws ClassNotFoundException {
    return Class.forName(getProperty(ADD_SERVICE_HOST_GROUP_STRATEGY)).asSubclass(HostGroupStrategy.class);
  }
@return The class of the host group strategy for add service requests.
@throws ClassNotFoundException if the specified class is not found
@throws ClassCastException if the specified class is not a subclass of {@link HostGroupStrategy}
ambari-server/src/main/java/org/apache/ambari/server/configuration/Configuration.java