I discovered this TODO in the code while debugging why an additional @ZKBIND annotation didn't trigger a save binding on a custom event

https://github.com/zkoss/zk/blob/v8.0.2/zkbind/src/org/zkoss/bind/impl/AnnotationUtil.java#L77

e.g. trying to @save the textbox value on a custom event

@ComponentAnnotation("@ZKBIND(ACCESS=both, SAVE_EVENT=onFormattedInput, LOAD_REPLACEMENT=rawValue, LOAD_TYPE=java.lang.String)")
@Override
    public Object getValue() {
       ... 
    }

it needs to be decided whether multiple annotations for the same property
1. are allowed => implement this feature => multiple listeners (favored option)
2. are ignored => throw an exception or log a warning that something gets ignored to give the developer feedback that something won't work as expected