public void addFilter(Class<?> clazz, SerializeFilter filter) {
	    ObjectSerializer serializer = getObjectWriter(clazz);
	    
	    if (serializer instanceof SerializeFilterable) {
	        SerializeFilterable filterable = (SerializeFilterable) serializer;
	        
	        if (this != SerializeConfig.globalInstance) {
	            if (filterable == MapSerializer.instance) {
	                MapSerializer newMapSer = new MapSerializer();
	                this.put(clazz, newMapSer);
	                newMapSer.addFilter(filter);
	                return;
	            }
	        }
	        
	        filterable.addFilter(filter);
	    }
	}
add class level serialize filter
@since 1.2.10
src/main/java/com/alibaba/fastjson/serializer/SerializeConfig.java