private Object convertField(
            JsonToRowDataConverter fieldConverter, String fieldName, JsonNode field) {
        if (field == null) {
            if (failOnMissingField) {
                throw new JsonParseException("Could not find field with name '" + fieldName + "'.");
            } else {
                return null;
            }
        } else {
            return fieldConverter.convert(field);
        }
    }
Creates a runtime converter which assuming input object is not null.
inlong-sort/sort-flink/base/src/main/java/org/apache/inlong/sort/base/format/JsonToRowDataConverters.java