src/main/java/org/efaps/ui/wicket/components/LabelComponent.java
@Override
    protected void onRender()
    {
        final IMarkupFragment markup = getMarkup();
        if (markup == null) {
            throw new MarkupException("Markup not found. Component: " + toString());
        }

        final MarkupStream markupStream = new MarkupStream(markup);

        // Get mutable copy of next tag
        final ComponentTag openTag = markupStream.getTag();
        final ComponentTag tag = openTag.mutable();

        // Call any tag handler
        onComponentTag(tag);

        // If we're an openclose tag
        if (!tag.isOpenClose() && !tag.isOpen()) {
            // We were something other than <tag> or <tag/>
            markupStream.throwMarkupException("Method renderComponent called on bad markup element: " + tag);
        }

        if (tag.isOpenClose() && openTag.isOpen()) {
            markupStream.throwMarkupException("You can not modify a open tag to open-close: " + tag);
        }

        markupStream.next();

        getMarkupSourcingStrategy().onComponentTagBody(this, markupStream, tag);
    }
@Override
    protected void onRender()
    {
        final IMarkupFragment markup = getMarkup();
        if (markup == null) {
            throw new MarkupException("Markup not found. Component: " + toString());
        }

        final MarkupStream markupStream = new MarkupStream(markup);

        // Get mutable copy of next tag
        final ComponentTag openTag = markupStream.getTag();
        final ComponentTag tag = openTag.mutable();

        // Call any tag handler
        onComponentTag(tag);

        // If we're an openclose tag
        if (!tag.isOpenClose() && !tag.isOpen()) {
            // We were something other than <tag> or <tag/>
            markupStream.throwMarkupException("Method renderComponent called on bad markup element: " + tag);
        }

        if (tag.isOpenClose() && openTag.isOpen()) {
            markupStream.throwMarkupException("You can not modify a open tag to open-close: " + tag);
        }

        markupStream.next();

        getMarkupSourcingStrategy().onComponentTagBody(this, markupStream, tag);
    }
Method is overwritten to prevent the annoing warnings from Component to come up.
The warning come up due to the reason that this component moves the tags from parent
element to its child.