presto-main/src/main/java/io/prestosql/operator/scalar/JsonFunctions.java/JsonFunctions/varcharJsonExtractScalar
class JsonFunctions:    @ScalarFunction("json_extract_scalar")
    @SqlNullable
    @LiteralParameters("x")
    @SqlType("varchar(x)")
    public static Slice varcharJsonExtractScalar(@SqlType("varchar(x)") Slice json, @SqlType(JsonPathType.NAME) JsonPath jsonPath)
    {
        return JsonExtract.extract(json, jsonPath.getScalarExtractor());
    }