#vulnerable code 
                                protected SettableBeanProperty _resolvedObjectIdProperty(DeserializationContext ctxt,
            SettableBeanProperty prop) throws JsonMappingException
    {
        ObjectIdInfo objectIdInfo = prop.getObjectIdInfo();
        JsonDeserializer<Object> valueDeser = prop.getValueDeserializer();
        ObjectIdReader objectIdReader = valueDeser.getObjectIdReader();
        if (objectIdInfo == null && objectIdReader == null) {
            return prop;
        }
        return new ObjectIdReferenceProperty(prop, objectIdInfo);
    } 
                            #location 6 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                protected SettableBeanProperty _resolvedObjectIdProperty(DeserializationContext ctxt,
            SettableBeanProperty prop) throws JsonMappingException
    {
        ObjectIdInfo objectIdInfo = prop.getObjectIdInfo();
        JsonDeserializer<Object> valueDeser = prop.getValueDeserializer();
        ObjectIdReader objectIdReader = (valueDeser == null) ? null : valueDeser.getObjectIdReader();
        if (objectIdInfo == null && objectIdReader == null) {
            return prop;
        }
        return new ObjectIdReferenceProperty(prop, objectIdInfo);
    }