public Element setNamespace(Namespace namespace) {
    if (namespace == null) {
      namespace = Namespace.NO_NAMESPACE;
    }

    if (additionalNamespaces != null) {
      String reason = Verifier.checkNamespaceCollision(namespace, additionalNamespaces);
      if (reason != null) {
        throw new IllegalAddException(this, namespace, reason);
      }
    }
    if (hasAttributes()) {
      for (Attribute a : getAttributes()) {
        final String reason =
          Verifier.checkNamespaceCollision(namespace, a);
        if (reason != null) {
          throw new IllegalAddException(this, namespace, reason);
        }
      }
    }

    this.namespace = namespace;
    return this;
  }
public Element setNamespace(Namespace namespace)