This is an GraphQL sample application showcasing how the Blaze-Persistence GraphQL integration can be used to develop GraphQL interfaces with ease.
Just deploy the produced WAR file to a Java/Jakarta EE application server and navigate to http://localhost:8080/graphql-ui where you can run your GraphQL queries. You will see that the queries exposed there use the GraphQL Relay spec to implement pagination through cursors. You can take a look at the generated queries to further understand what happens or you take a look into the documentation for more information on the topic.
Another thing that you will see from the generated queries is that the GraphQL selection list actually alters what is selected in the SQL query!