@Override
    public String buildContext() {
        final String plugins = ((Collection<?>) getSource())
                .stream()
                .map(s -> ((PluginDO) s).getName())
                .collect(Collectors.joining(","));
        return String.format("the plugins[%s] is %s", plugins, StringUtils.lowerCase(getType().getType().toString()));
    }
Create a new {@code PluginChangedEvent}.operator is unknown.

@param source   Current plugin state
@param before   Before the change plugin state
@param type     event type
@param operator operator
shenyu-admin/src/main/java/org/apache/shenyu/admin/model/event/plugin/BatchPluginChangedEvent.java