static ExecutionIdGenerator of() {
        return (requestContext, query, operationName, graphqlContext) -> ExecutionId.from(
                requestContext.id().text());
    }
Returns the default {@link ExecutionIdGenerator} that uses {@link ServiceRequestContext#id()}
as the execution ID.
graphql/src/main/java/com/linecorp/armeria/server/graphql/ExecutionIdGenerator.java