presto-main/src/main/java/io/prestosql/operator/annotations/FunctionsParserHelper.java/FunctionsParserHelper/parseLiteralParameters
class FunctionsParserHelper:    public static Set<String> parseLiteralParameters(Method method)
    {
        LiteralParameters literalParametersAnnotation = method.getAnnotation(LiteralParameters.class);
        if (literalParametersAnnotation == null) {
            return ImmutableSet.of();
        }

        return ImmutableSet.copyOf(literalParametersAnnotation.value());
    }