BREAKING CHANGE: add response object emptiness check (#19)

Co-authored-by: ProcessOut Fountain <internal@processout.com>

BREAKING CHANGE:

BREAKING CHANGE: add response object emptiness check (#19)

Co-authored-by: ProcessOut Fountain <internal@processout.com>

BREAKING CHANGE:

feat: add customer and invoice reference_id; add balances customer ac…

…tion (#17)

Co-authored-by: ProcessOut Fountain <internal@processout.com>

feat: Update library (#16)

Co-authored-by: ProcessOut Fountain <internal@processout.com>

feat: add-new-operation-error-message-field (#15)

Co-authored-by: ProcessOut Fountain <internal@processout.com>

feat: Add custom action structure to the create token flow (#12)

Co-authored-by: ProcessOut Fountain <internal@processout.com>

BREAKING CHANGE: breaking: change response types for invoices-authori…

…ze, invoices-capture, invoices-native-payment; breaking: create/update card; add invoice expiry; add invoice qr_code; add invoice delete; add project public metadata; add hosted payment page support (#11)

Co-authored-by: ProcessOut Fountain <internal@processout.com>

feat: add auto_capture_at field within the invoice object (#9)

Co-authored-by: ProcessOut Fountain <internal@processout.com>

feat: Add create/update card request fields; SFTPSettings (#8)

Co-authored-by: ProcessOut Fountain <internal@processout.com>

feat: Add create/update card; PayoutItemAmountBreakdowns (#7)

Co-authored-by: ProcessOut Fountain <internal@processout.com>