DataplanePublicApiControler completable future failure messages are returned as contatenated string

[rafaelmag110]

Bug Report

Describe the Bug

In the DataplanePublicApiV2Controler, if the CompletableFuture handled by the processRequest method has a result with multiple failure messages, these messages will all be concatenated into a single string, even though the TransferErrorResponse handles a list of errors.

Expected Behavior

Since the end result to the client is a list of errors, it would be expected that response includes an actual list of errors and not a concatenated string of errors.

Observed Behavior

Here a Details list should be a single error, but all are concatenated.

[rafaelmag110]

I think this is a good first issue. Can label it anymore since I've lost my contributor status :(