private String rendererNames() {
        StringBuilder r = new StringBuilder();
        for (Renderer<Result> c : allComponents()) {
            if (!r.isEmpty())
                r.append(", ");
            r.append(c.getId().stringValue());
        }
        return r.toString();
    }
Returns the requested renderer.

@param format the id or format alias of the renderer to return. If null is passed the default renderer
              is returned
@throws IllegalArgumentException if the renderer cannot be resolved
container-search/src/main/java/com/yahoo/search/rendering/RendererRegistry.java