Trying to use private method of parent

https://github.com/howtographql/graphql-java/blob/master/src/main/java/com/howtographql/hackernews/GraphQLEndpoint.java

```
    public GraphQLEndpoint() {
        super(buildSchema());
    }
```
Currently, the buildSchema of SimpleGraphQLServlet  is private - this code does not work.