Improved: suppresses 2 warnings related to deprecated CSVFormat.DEFAULT.withHeader()

Also adds a try-with-ressource in InvoiceServices::importInvoice to properly
close csvReader on returns. Hence removes an useless csvReader.close().

Several comments about Eclipse giving wrong advice
<<Resource leak: '<unassigned Closeable value>' is not closed at this location>>
It's OK, we are inside try-with-ressources.

Finally removes a redundant final in PartyServices::importParty

Conflicts in InvoiceServices.java handled by hand
2 files changed