@Override
    public String buildContext() {
        final NamespacePluginVO after = (NamespacePluginVO) getAfter();
        if (Objects.isNull(getBefore())) {
            return String.format("the namespace [%s] plugin [%s] is %s", after.getNamespaceId(), after.getName(), StringUtils.lowerCase(getType().getType().toString()));
        }
        return String.format("the namespace [%s] plugin [%s] is %s : %s", after.getNamespaceId(), after.getName(), StringUtils.lowerCase(getType().getType().toString()), contrast());
        
    }
Create a new {@code PluginChangedEvent}.operator is unknown.

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