code: @Override
      public Set<URI> listOperations(URI serviceUri) {
          if (serviceUri == null) {
              return ImmutableSet.of();
          }
  
          ImmutableSet.Builder<URI> result = ImmutableSet.builder();
          for (URI operation : this.svcOpMap.get(serviceUri)) {
              result.add(operation);
          }
  
          return result.build();
      }
docs: Obtains the list of operation URIs for a given Operation
  
  @param serviceUri the service URI
  @return a List of URIs with the operations provided by the service. If there are no operations, the List should be empty NOT null.