code: @Override
      public Set<URI> listElementsAnnotatedWith(URI modelReference) {
          if (modelReference == null) {
              return ImmutableSet.of();
          }
  
          String queryStr = new StringBuilder()
                  .append("SELECT DISTINCT ?element WHERE { \n")
                  .append(" GRAPH ?g { \n")
                  .append(" ?element <").append(SAWSDL.modelReference.getURI()).append("> <").append(modelReference.toASCIIString()).append("> .")
                  .append(" } \n ")
                  .append("} \n ")
                  .toString();
  
          return this.graphStoreManager.listResourcesByQuery(queryStr, "element");
      }
docs: Given a modelReference, this method finds all the elements that have been annotated with it. This method finds
  exact annotations. Note that the elements can be services, operations, inputs, etc.
  
  @param modelReference the actual annotation we are looking for
  @return a set of URIs for elements that have been annotated with the requested modelReferences.