presto-main/src/main/java/io/prestosql/operator/scalar/JsonFunctions.java/JsonFunctions/castCharToJsonPath
class JsonFunctions:    @ScalarOperator(OperatorType.CAST)
    @LiteralParameters("x")
    @SqlType(JsonPathType.NAME)
    public static JsonPath castCharToJsonPath(@LiteralParameter("x") Long charLength, @SqlType("char(x)") Slice pattern)
    {
        return new JsonPath(padSpaces(pattern, charLength.intValue()).toStringUtf8());
    }