a.) Am i right? REST API (list payments) show only REST payments?
Yes, the REST Payments API will only list the payments that have been made using such API.
b.) if a is true, is there another workaround to request full list of all payments (including refunds etc.)?
You could use our classic TransactionSearch and GetTransactionDetails API to list all of the transactions in your account:
https://developer.paypal.com/docs/classic/api/merchant/TransactionSearch_API_Operation_NVP/
https://developer.paypal.com/docs/classic/api/merchant/GetTransactionDetails_API_Operation_NVP/
c.) Where do i find working examples for the "Classic" API to list ALL payments?
Our classic SDKs should have examples for each API:
https://developer.paypal.com/docs/classic/api/nvpsoap-sdks/
For example, if you use .NET:
https://github.com/paypal/merchant-sdk-dotnet/tree/master/Samples/PayPalAPISample/APICalls
Alternatively, you can build your own NVP POST based in our API reference.
REgarding the API credentials, we would recommend to use API Signature, that can be obtained from this direct link:
https://www.paypal.com/cgi-bin/webscr?cmd=_profile-api-access
If you already have an API Certificate in place, you will need to remove it before being able to request a new API Signature.
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