public Map<String, String> getRankProperties(SerializationContext context) {
        if ("".equals(name)) return Map.of();
        Deque<String> path = new LinkedList<>();
        String serializedRoot = root.toString(new StringBuilder(), context, path, null).toString();
        Map<String, String> serializedExpressions = context.serializedFunctions();
        serializedExpressions.put(propertyName(name), serializedRoot);
        return serializedExpressions;
    }
Creates the necessary rank properties required to implement this expression.

@param context context for serialization
@return a map of the named rank properties required to implement this expression
searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/RankingExpression.java