public static ServiceRequestContext get(DataFetchingEnvironment environment) {
        requireNonNull(environment, "environment");
        return get(environment.getGraphQlContext());
    }
Retrieves the current {@link ServiceRequestContext} from the specified {@link DataFetchingEnvironment}.
For example:
<pre>{@code
new DataFetcher<>() {
    @Override
    public String get(DataFetchingEnvironment env) throws Exception {
        final ServiceRequestContext ctx = GraphqlServiceContexts.get(env);
        // ...
    }
};
}</pre>

@throws IllegalStateException if the specified {@link DataFetchingEnvironment} doesn't contain
                              a {@link ServiceRequestContext}.
graphql/src/main/java/com/linecorp/armeria/server/graphql/GraphqlServiceContexts.java