A Ratpack GraphQL query handler

handler.java

public class GraphQLHandler implements Handler {
// ...
@Override
public void handle(Context context) throws Exception {
        context.parse(Map.class).then(payload -> {
            Map<String, Object> variables = 
                    (Map<String, Object>) payload.get("variables");
            ExecutionInput executionInput = 
                    ExecutionInput.newExecutionInput()
                    .query(payload.get("query").toString())
                    .variables(variables)
                    .build();
            final ExecutionResult executionResult = 
                    graphql.execute(executionInput);
            Map<String, Object> result = new LinkedHashMap<>();
            if (executionResult.getErrors().isEmpty()) {
                result.put("data", executionResult.getData());
            } else {
                result.put("errors", executionResult.getErrors());
            }
            context.render(json(result));
        });
    }
}