anchor.diff:  {@link examples.GraphQLExamples#completionStageDataFetcher}
   ----
   
  -=== Fetching data with callback-based APIs
  +=== Working with callback-based APIs
   
   Implementing a data fetcher that returns a `CompletionStage` is not a complex task.
   But when you work with Vert.x callback-based APIs, it requires a bit of boilerplate.
  
positive.code: 
  TIP: The {@link io.vertx.ext.web.handler.graphql.GraphQLHandler} does not require a {@link io.vertx.ext.web.handler.BodyHandler} to read `POST` requests content.
  
  === GraphiQL client
  
  As you are building your application, testing your GraphQL queries in https://github.com/graphql/graphiql[GraphiQL] can be handy.
  
  
negative.code: 
  TIP: {@link io.vertx.ext.web.handler.graphql.schema.VertxPropertyDataFetcher} wraps a `PropertyDataFetcher` so you can still use it with domain objects.
  
  === Batch loading
  
  Dataloaders help you to load data efficiently by batching fetch requests and caching results.
  
  