code: @Override
      protected String doBackward(final String b) {
          LOGGER.trace("Converting identifier from external to internal...");
          String result = b;
          for (final String rdfNamespace : rdfNamespacesToJcrNamespaces.keySet()) {
              LOGGER.trace("Replacing namespace: {} with: {}", rdfNamespace, rdfNamespacesToJcrNamespaces
                      .get(rdfNamespace));
              result = result.replace(rdfNamespace, rdfNamespacesToJcrNamespaces.get(rdfNamespace));
          }
          return result;
      }
docs: /*
  (non-Javadoc)
  @see
  org.fcrepo.kernel.api.identifiers.InternalIdentifierConverter#doBackward
  (java.lang.String)