code: public ImmutableList<InstanceInfo> getRoleInstances(String roleName) {
          return getRoleInstancesWithMetadataImpl(roleName, Collections.<String, String>emptyMap());
      }
docs: Retrieve information about instances of a particular role from the Conqueso Server.
  @param roleName the role to retrieve
  @return the information about the instances of the given role
  @throws ConquesoCommunicationException if there's an error communicating with the Conqueso Server.