Add support for SellerReceivableBreakdown (#178)

* Add support for SellerReceivableBreakdown

https://developer.paypal.com/docs/api/orders/v2/#orders_capture

* Update types.go

* Update types.go

types.go

@@ -590,11 +590,32 @@ type (
 		UpdateTime    *time.Time             `json:"update_time,omitempty"`
 	}
 
+	// ExchangeRate struct
+	//
+	// https://developer.paypal.com/docs/api/orders/v2/#definition-exchange_rate
+	ExchangeRate struct {
+		SourceCurrency string `json:"source_currency"`
+		TargetCurrency string `json:"target_currency"`
+		Value          string `json:"value"`
+	}
+
+	// SellerReceivableBreakdown has the detailed breakdown of the capture activity.
+	SellerReceivableBreakdown struct {
+		GrossAmount                   *Money        `json:"gross_amount,omitempty"`
+		PaypalFee                     *Money        `json:"paypal_fee,omitempty"`
+		PaypalFeeInReceivableCurrency *Money        `json:"paypal_fee_in_receivable_currency,omitempty"`
+		NetAmount                     *Money        `json:"net_amount,omitempty"`
+		ReceivableAmount              *Money        `json:"receivable_amount,omitempty"`
+		ExchangeRate                  *ExchangeRate `json:"exchange_rate,omitempty"`
+		PlatformFees                  []PlatformFee `json:"platform_fees,omitempty"`
+	}
+
 	// CaptureAmount struct
 	CaptureAmount struct {
-		ID       string              `json:"id,omitempty"`
-		CustomID string              `json:"custom_id,omitempty"`
-		Amount   *PurchaseUnitAmount `json:"amount,omitempty"`
+		ID                        string                     `json:"id,omitempty"`
+		CustomID                  string                     `json:"custom_id,omitempty"`
+		Amount                    *PurchaseUnitAmount 	     `json:"amount,omitempty"`
+		SellerReceivableBreakdown *SellerReceivableBreakdown `json:"seller_receivable_breakdown,omitempty"`
 	}
 
 	// CapturedPayments has the amounts for a captured order