private String determineMaterializeProperties() {
        final Optional<String> mp = GremlinScriptChecker.parse(gremlinArgument.toString()).getMaterializeProperties();
        if (mp.isPresent())
            return mp.get().equals(Tokens.MATERIALIZE_PROPERTIES_TOKENS)
                    ? Tokens.MATERIALIZE_PROPERTIES_TOKENS
                    : Tokens.MATERIALIZE_PROPERTIES_ALL;

        final String materializeProperties = requestMessage.getField(Tokens.ARGS_MATERIALIZE_PROPERTIES);
        // all options except MATERIALIZE_PROPERTIES_TOKENS treated as MATERIALIZE_PROPERTIES_ALL
        return Tokens.MATERIALIZE_PROPERTIES_TOKENS.equals(materializeProperties)
                ? Tokens.MATERIALIZE_PROPERTIES_TOKENS
                : Tokens.MATERIALIZE_PROPERTIES_ALL;
    }
Signal that the server has started processing the response.
gremlin-server/src/main/java/org/apache/tinkerpop/gremlin/server/Context.java