docs: private void generatePeerLinks(final Metadata m, final Element e) {
          for (final PeerLink peerLink : m.getPeerLinks()) {
              final Element peerLinkElement = new Element("peerLink", NS);
              addNotNullAttribute(peerLinkElement, "type", peerLink.getType());
              addNotNullAttribute(peerLinkElement, "href", peerLink.getHref());
              if (peerLinkElement.hasAttributes()) {
                  e.addContent(peerLinkElement);
              }
          }
      }