private DateTimeFormatter getDateTimeFormatter(String pattern) {
        DateTimeFormatter formatter = INPUT_FORMATTERS.get(pattern);
        if (formatter == null) {
            formatter = DateTimeFormatter.ofPattern(pattern);
            INPUT_FORMATTERS.put(pattern, formatter);
        }
        return formatter;
    }
ToDateFunction  ->  to_date(str[, format])
description:
- Return NULL if 'str' is NULL;
- Return the result of converting the date string 'str' to a date in the format 'format'(default is 'yyyy-MM-dd') .
inlong-sdk/transform-sdk/src/main/java/org/apache/inlong/sdk/transform/process/function/temporal/ToDateFunction.java