feat(fedex): add two response models for MFA workflow

Created two separate model classes to properly deserialize different
response types in the FedEx MFA workflow:

1. FedExAccountValidationResponse - returned by registerAddress and
   requestPin endpoints when further validation is required. Contains
   email_address, phone_number, and options for PIN delivery methods.

2. FedexRegistration - returned by validatePin and submitInvoice
   endpoints when validation is complete. Contains type and credentials
   for the registered account.

Updated VCR cassettes with realistic response structures matching the
actual API responses. Added comprehensive test assertions that verify
both response types deserialize correctly and contain expected fields.

Author: lanej

src/main/java/com/easypost/model/FedExAccountValidationResponse.java

@@ -0,0 +1,14 @@
+package com.easypost.model;
+
+import com.google.gson.annotations.SerializedName;
+import java.util.Map;
+import lombok.Getter;
+
+@Getter
+public final class FedExAccountValidationResponse extends EasyPostResource {
+    @SerializedName("email_address")
+    private String emailAddress;
+    private Map<String, String> options;
+    @SerializedName("phone_number")
+    private String phoneNumber;
+}

src/main/java/com/easypost/model/FedexRegistration.java

@@ -1,9 +1,10 @@
 package com.easypost.model;
 
+import java.util.Map;
 import lombok.Getter;
 
 @Getter
 public final class FedexRegistration extends EasyPostResource {
-    private String status;
-    private String message;
+    private String type;
+    private Map<String, String> credentials;
 }

src/main/java/com/easypost/service/FedexRegistrationService.java

@@ -3,6 +3,7 @@
 import com.easypost.exception.EasyPostException;
 import com.easypost.http.Requestor;
 import com.easypost.http.Requestor.RequestMethod;
+import com.easypost.model.FedExAccountValidationResponse;
 import com.easypost.model.FedexRegistration;
 
 import java.util.HashMap;
@@ -33,12 +34,12 @@ public class FedexRegistrationService {
      * @param postalCode         Postal/ZIP code.
      * @param countryCode        Country code (e.g., "US").
      * @param carrierAccountId   EasyPost carrier account ID to update.
-     * @return FedexRegistration object.
+     * @return FedExAccountValidationResponse object with next steps (PIN or invoice validation).
      * @throws EasyPostException when the request fails.
      */
-    public FedexRegistration registerAddress(final String fedexAccountNumber, final String name, final String street1,
-            final String city, final String state, final String postalCode, final String countryCode,
-            final String carrierAccountId) throws EasyPostException {
+    public FedExAccountValidationResponse registerAddress(final String fedexAccountNumber, final String name,
+            final String street1, final String city, final String state, final String postalCode,
+            final String countryCode, final String carrierAccountId) throws EasyPostException {
         Map<String, Object> addressValidation = new HashMap<>();
         addressValidation.put("name", name);
         addressValidation.put("street1", street1);
@@ -67,15 +68,16 @@ public FedexRegistration registerAddress(final String fedexAccountNumber, final
      *                           If "address_validation.name" is not provided, a UUID will be
      *                           auto-generated.
      *                           Optional: "easypost_details" object with "carrier_account_id".
-     * @return FedexRegistration object.
+     * @return FedExAccountValidationResponse object with next steps (PIN or invoice validation).
      * @throws EasyPostException when the request fails.
      */
-    public FedexRegistration registerAddress(final String fedexAccountNumber, final Map<String, Object> params)
-            throws EasyPostException {
+    public FedExAccountValidationResponse registerAddress(final String fedexAccountNumber,
+            final Map<String, Object> params) throws EasyPostException {
         Map<String, Object> wrappedParams = wrapAddressValidation(params);
         String endpoint = String.format("fedex_registrations/%s/address", fedexAccountNumber);
 
-        return Requestor.request(RequestMethod.POST, endpoint, wrappedParams, FedexRegistration.class, client);
+        return Requestor.request(RequestMethod.POST, endpoint, wrappedParams, FedExAccountValidationResponse.class,
+                client);
     }
 
     /**
@@ -84,10 +86,10 @@ public FedexRegistration registerAddress(final String fedexAccountNumber, final
      *
      * @param fedexAccountNumber The FedEx account number.
      * @param pinMethodOption    The PIN delivery method: "SMS", "CALL", or "EMAIL".
-     * @return FedexRegistration object.
+     * @return FedExAccountValidationResponse object confirming PIN was sent.
      * @throws EasyPostException when the request fails.
      */
-    public FedexRegistration requestPin(final String fedexAccountNumber, final String pinMethodOption)
+    public FedExAccountValidationResponse requestPin(final String fedexAccountNumber, final String pinMethodOption)
             throws EasyPostException {
         Map<String, Object> pinMethod = new HashMap<>();
         pinMethod.put("option", pinMethodOption);
@@ -106,14 +108,14 @@ public FedexRegistration requestPin(final String fedexAccountNumber, final Strin
      * @param params             Map of parameters containing "pin_method" with "option" field.
      *                           The "option" value must be one of "SMS", "CALL", or "EMAIL".
      *                           Example: {"pin_method": {"option": "SMS"}}
-     * @return FedexRegistration object.
+     * @return FedExAccountValidationResponse object confirming PIN was sent.
      * @throws EasyPostException when the request fails.
      */
-    public FedexRegistration requestPin(final String fedexAccountNumber, final Map<String, Object> params)
+    public FedExAccountValidationResponse requestPin(final String fedexAccountNumber, final Map<String, Object> params)
             throws EasyPostException {
         String endpoint = String.format("fedex_registrations/%s/pin", fedexAccountNumber);
 
-        return Requestor.request(RequestMethod.POST, endpoint, params, FedexRegistration.class, client);
+        return Requestor.request(RequestMethod.POST, endpoint, params, FedExAccountValidationResponse.class, client);
     }
 
     /**

src/test/cassettes/fedex_registration/register_address.json

@@ -1,13 +1,15 @@
 package com.easypost;
 
 import com.easypost.exception.EasyPostException;
+import com.easypost.model.FedExAccountValidationResponse;
 import com.easypost.model.FedexRegistration;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
 
 import java.util.HashMap;
 import java.util.Map;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertInstanceOf;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 
@@ -49,11 +51,16 @@ public void testRegisterAddress() throws EasyPostException {
         params.put("address_validation", addressValidation);
         params.put("easypost_details", easypostDetails);
 
-        FedexRegistration registration = vcr.client.fedexRegistration.registerAddress(TEST_FEDEX_ACCOUNT_NUMBER,
-                params);
+        FedExAccountValidationResponse response = vcr.client.fedexRegistration
+                .registerAddress(TEST_FEDEX_ACCOUNT_NUMBER, params);
 
-        assertInstanceOf(FedexRegistration.class, registration);
-        assertNotNull(registration.getId());
+        assertInstanceOf(FedExAccountValidationResponse.class, response);
+        assertNotNull(response.getId());
+        assertNotNull(response.getEmailAddress());
+        assertNotNull(response.getPhoneNumber());
+        assertNotNull(response.getOptions());
+        assertEquals("test@example.com", response.getEmailAddress());
+        assertEquals("+1234567890", response.getPhoneNumber());
     }
 
     /**
@@ -71,10 +78,14 @@ public void testRequestPin() throws EasyPostException {
         Map<String, Object> params = new HashMap<>();
         params.put("pin_method", pinMethod);
 
-        FedexRegistration registration = vcr.client.fedexRegistration.requestPin(TEST_FEDEX_ACCOUNT_NUMBER, params);
+        FedExAccountValidationResponse response = vcr.client.fedexRegistration.requestPin(TEST_FEDEX_ACCOUNT_NUMBER,
+                params);
 
-        assertInstanceOf(FedexRegistration.class, registration);
-        assertNotNull(registration.getId());
+        assertInstanceOf(FedExAccountValidationResponse.class, response);
+        assertNotNull(response.getId());
+        assertNotNull(response.getEmailAddress());
+        assertNotNull(response.getPhoneNumber());
+        assertNotNull(response.getOptions());
     }
 
     /**
@@ -101,6 +112,9 @@ public void testValidatePin() throws EasyPostException {
 
         assertInstanceOf(FedexRegistration.class, registration);
         assertNotNull(registration.getId());
+        assertEquals("FedexAccount", registration.getType());
+        assertNotNull(registration.getCredentials());
+        assertEquals("123456789", registration.getCredentials().get("account_number"));
     }
 
     /**
@@ -130,6 +144,9 @@ public void testSubmitInvoice() throws EasyPostException {
 
         assertInstanceOf(FedexRegistration.class, registration);
         assertNotNull(registration.getId());
+        assertEquals("FedexAccount", registration.getType());
+        assertNotNull(registration.getCredentials());
+        assertEquals("123456789", registration.getCredentials().get("account_number"));
     }
 
 }