@Override
                    public void sendResult(String operationId, ExecutionResult executionResult)
                            throws JsonProcessingException {
                        writeNext(out, operationId, executionResult);
                    }
Receives an event and returns a response if one should be sent.
graphql/src/main/java/com/linecorp/armeria/server/graphql/GraphqlWSSubProtocol.java