code: public String getHrefResolved(final String relativeUri) {
          if (Atom10Parser.isAbsoluteURI(relativeUri)) {
              return relativeUri;
          } else if (baseURI != null && collectionElement != null) {
              final int lastslash = baseURI.lastIndexOf("/");
              return Atom10Parser.resolveURI(baseURI.substring(0, lastslash), collectionElement, relativeUri);
          }
          return null;
      }
docs: Get resolved URI using collection's baseURI, or null if impossible to determine