code: public List<EntitySummary> getEntitiesFromApplication(String brooklynId) throws IOException {
          Invocation invocation = getJerseyClient().target(getEndpoint() + "/v1/applications/" + brooklynId + "/entities")
                  .request().buildGet();
  
          return invocation.invoke().readEntity(new GenericType<List<EntitySummary>>(){});
      }
docs: Creates a proxied HTTP GET request to Apache Brooklyn to retrieve the Application's Entities
  
  @param brooklynId of the desired application to fetch. This ID may differ from SeaClouds Application ID
  @return List<EntitySummary> with all the children entities of the application