Now that JDK 17 is the baseline for v5, the FlatFileItemReaderBuilder can use java.lang.Class#isRecord to detect if the type of items is a record or a regular class and configure the right FieldSetMapper accordingly (ie RecordFieldSetMapper for records and BeanWrapperFieldSetMapper for regular classes).

The goal of this issue is to implement this idea to make the configuration of the right FieldSetMapper transparent to the user.