Init multi payment endpoint and samples added

src/main/java/io/craftgate/adapter/PaymentAdapter.java

@@ -270,6 +270,12 @@ public InstantTransferBanksResponse retrieveActiveBanks() {
                 InstantTransferBanksResponse.class);
     }
 
+    public InitMultiPaymentResponse initMultiPayment(InitMultiPaymentRequest initMultiPaymentRequest) {
+        String path = "/payment/v1/multi-payments/init";
+        return HttpClient.post(requestOptions.getBaseUrl() + path, createHeaders(initMultiPaymentRequest, path, requestOptions),
+                initMultiPaymentRequest, InitMultiPaymentResponse.class);
+    }
+
     public MultiPaymentResponse retrieveMultiPayment(String token) {
         String path = "/payment/v1/multi-payments/" + token;
         return HttpClient.get(requestOptions.getBaseUrl() + path, createHeaders(path, requestOptions), MultiPaymentResponse.class);

src/main/java/io/craftgate/model/WebhookEventType.java

@@ -14,5 +14,8 @@ public enum WebhookEventType {
     WALLET_TX_CREATED,
     BNPL_NOTIFICATION,
     BANK_ACCOUNT_TRACKING_RECORD,
-    BKM_EXPRESS_PAYMENT_NOTIFICATION
+    BKM_EXPRESS_PAYMENT_NOTIFICATION,
+
+    MULTI_PAYMENT_COMPLETED,
+    MULTI_PAYMENT_EXPIRED
 }

src/main/java/io/craftgate/request/InitMultiPaymentRequest.java

@@ -0,0 +1,51 @@
+package io.craftgate.request;
+
+import io.craftgate.model.*;
+import io.craftgate.request.dto.PaymentItem;
+import lombok.Builder;
+import lombok.Data;
+
+import java.math.BigDecimal;
+import java.util.List;
+import java.util.Map;
+
+@Data
+@Builder
+public class InitMultiPaymentRequest {
+
+    private BigDecimal price;
+    private BigDecimal paidPrice;
+    private Currency currency;
+    private PaymentGroup paymentGroup;
+    private PaymentSource paymentSource;
+    private String conversationId;
+    private String externalId;
+    private String callbackUrl;
+
+    @Builder.Default
+    protected PaymentPhase paymentPhase = PaymentPhase.AUTH;
+    private String paymentChannel;
+
+    private List<PaymentMethod> enabledPaymentMethods;
+
+    private String cardUserKey;
+
+    private Long buyerMemberId;
+    private boolean allowOnlyCreditCard;
+    private boolean forceAuthForNonCreditCards;
+    private boolean allowOnlyStoredCards;
+    private boolean allowInstallmentOnlyCommercialCards;
+    private boolean alwaysStoreCardAfterPayment;
+    private boolean disableStoreCard;
+    private boolean forceThreeDS;
+
+    private String masterpassGsmNumber;
+    private String masterpassUserId;
+    private String apmUserIdentity;
+
+    private List<PaymentItem> items;
+
+    private Long ttl;
+    private Integer maximumSplitPaymentCount;
+    private Map<String, Object> additionalParams;
+}

src/main/java/io/craftgate/response/InitMultiPaymentResponse.java

@@ -0,0 +1,13 @@
+package io.craftgate.response;
+
+import lombok.Data;
+
+import java.time.LocalDateTime;
+
+@Data
+public class InitMultiPaymentResponse {
+
+    protected String token;
+    protected String pageUrl;
+    protected LocalDateTime tokenExpireDate;
+}

src/test/java/io/craftgate/sample/PaymentSample.java

@@ -2188,6 +2188,41 @@ void update_payment_transaction() {
         assertEquals(request.getSubMerchantMemberPrice().doubleValue(), response.getSubMerchantMemberPrice().doubleValue());
     }
 
+    @Test
+    void init_multi_payment() {
+        List<PaymentItem> items = new ArrayList<>();
+        items.add(PaymentItem.builder()
+                .name("item 1")
+                .externalId(UUID.randomUUID().toString())
+                .price(BigDecimal.valueOf(30))
+                .build());
+
+        items.add(PaymentItem.builder()
+                .name("item 2")
+                .externalId(UUID.randomUUID().toString())
+                .price(BigDecimal.valueOf(70))
+                .build());
+
+        InitMultiPaymentRequest request = InitMultiPaymentRequest.builder()
+                .price(BigDecimal.valueOf(100))
+                .paidPrice(BigDecimal.valueOf(100))
+                .buyerMemberId(7L)
+                .callbackUrl("https://www.your-website.com/craftgate-multi-payment-callback")
+                .currency(Currency.TRY)
+                .conversationId("456d1297-908e-4bd6-a13b-4be31a6e47d5")
+                .externalId("external_id-123456789")
+                .paymentGroup(PaymentGroup.LISTING_OR_SUBSCRIPTION)
+                .paymentPhase(PaymentPhase.AUTH)
+                .items(items)
+                .build();
+
+        InitMultiPaymentResponse response = craftgate.payment().initMultiPayment(request);
+
+        assertNotNull(response);
+        assertNotNull(response.getPageUrl());
+        assertNotNull(response.getToken());
+    }
+
     @Test
     void retrieve_multi_payment() {
         String token = "6d7e66b5-9b1c-4c1d-879a-2557b651096e";