MyFactoryConfigServiceClass.java

@Component(configurationFactory = true,
        policy = ConfigurationPolicy.REQUIRE, metatype = true, immediate = true)
@Service()
public class MyFactoryConfigServiceClass {
  
  //define config properties here as usual
  @Property(name = "some.prop.name", label = "My Property", value = "")
  private String myProperty
  
  /**
     * Activate the configuration.
     * 
     * @param ctx
     *            the component context object
     */
    @Activate
    protected void activate(final ComponentContext ctx) {
        log.info("activating instance of {}", this.getClass().getName());
        Dictionary<?, ?> props = ctx.getProperties();
        //init property values using PropertiesUtil
        myProperty = PropertiesUtil.toString(props.get("some.prop.name"),"");
    }
}

MyFactoryConsumer.java

@Component()
@Service()
public class MyFactoryConsumer {
  
  @Reference(referenceInterface = MyFactoryConfigServiceClass.class, cardinality = ReferenceCardinality.OPTIONAL_MULTIPLE,
            policy = ReferencePolicy.DYNAMIC)
    private List<MyFactoryConfigServiceClass> configs;
    
    protected synchronized void bindMyFactoryConfigServiceClass(final MyFactoryConfigServiceClass config) {
        if (configs == null) {
            configs = new ArrayList<MyFactoryConfigServiceClass>();
        }

        configs.add(config);
    }

    protected synchronized void unbindMyFactoryConfigServiceClass(final MyFactoryConfigServiceClass config) {
        configs.remove(config);
    }
  
}