Auth API - Support For PhoneNumber as a flexible identifier (#787)

### Changes

Added phone number as a flexible optional identifier for following
endpoints:

-  [Sign Up](https://auth0.com/docs/api/authentication#signup)

- [Change
Password](https://auth0.com/docs/api/authentication#change-password)

### References

- Internal API Change Docs

### Testing

- [x] This change adds test coverage

- [x] This change has been tested on the latest version of the
platform/language or why not

### Contributor Checklist

- [x] I agree to adhere to the [Auth0 General Contribution
Guidelines](https://github.com/auth0/open-source-template/blob/master/GENERAL-CONTRIBUTING.md).
- [x] I agree to uphold the [Auth0 Code of
Conduct](https://github.com/auth0/open-source-template/blob/master/CODE-OF-CONDUCT.md).

src/API/Authentication.php

@@ -139,6 +139,7 @@ public function dbConnectionsChangePassword(
                 'client_id' => $this->getConfiguration()->getClientId(ConfigurationException::requiresClientId()),
                 'email' => $email,
                 'connection' => $connection,
+                'phone_number' => $body['phone_number'] ?? null,
             ], $body]))
             ->withHeaders($headers)
             ->call();
@@ -170,6 +171,7 @@ public function dbConnectionsSignup(
                 'email' => $email,
                 'password' => $password,
                 'connection' => $connection,
+                'phone_number' => $body['phone_number'] ?? null,
             ], $body]))
             ->withHeaders($headers)
             ->call();

tests/Unit/API/AuthenticationTest.php

@@ -554,6 +554,52 @@
     expect($requestHeaders['header_testing'][0])->toEqual(123);
 });
 
+test('dbConnectionsSignup handles phone_number correctly', function (): void {
+    $clientSecret = uniqid();
+    $email = 'someone@somewhere.somehow';
+    $password = uniqid();
+    $connection = uniqid();
+    $phoneNumber = '+1234567890';
+
+    $this->configuration->setClientSecret($clientSecret);
+    $authentication = $this->sdk->authentication();
+    $authentication->getHttpClient()->mockResponses([HttpResponseGenerator::create()]);
+
+    // Test with phone_number
+    $authentication->dbConnectionsSignup($email, $password, $connection, ['phone_number' => $phoneNumber]);
+    $requestWithPhone = $authentication->getHttpClient()->getLastRequest()->getLastRequest();
+    $requestBodyWithPhone = json_decode($requestWithPhone->getBody()->__toString(), true);
+
+    $this->assertArrayHasKey('phone_number', $requestBodyWithPhone);
+    expect($requestBodyWithPhone['phone_number'])->toEqual($phoneNumber);
+
+    // Test without phone_number
+    $authentication->dbConnectionsSignup($email, $password, $connection);
+    $requestWithoutPhone = $authentication->getHttpClient()->getLastRequest()->getLastRequest();
+    $requestBodyWithoutPhone = json_decode($requestWithoutPhone->getBody()->__toString(), true);
+
+    $this->assertArrayNotHasKey('phone_number', $requestBodyWithoutPhone);
+});
+
+test('dbConnectionsSignup handles flexible identifiers and precedence', function (): void {
+    $clientSecret = uniqid();
+    $email = 'someone@somewhere.somehow';
+    $password = uniqid();
+    $connection = uniqid();
+    $phoneNumber = '+1234567890';
+
+    $this->configuration->setClientSecret($clientSecret);
+    $authentication = $this->sdk->authentication();
+    $authentication->getHttpClient()->mockResponses([HttpResponseGenerator::create()]);
+
+    $authentication->dbConnectionsSignup($email, $password, $connection, ['phone_number' => $phoneNumber]);
+    $request = $authentication->getHttpClient()->getLastRequest()->getLastRequest();
+    $requestBody = json_decode($request->getBody()->__toString(), true);
+
+    expect($requestBody['email'])->toEqual($email);
+    expect($requestBody['phone_number'])->toEqual($phoneNumber);
+});
+
 test('dbConnectionsChangePassword() is properly formatted', function(): void {
     $clientSecret = uniqid();
 
@@ -587,6 +633,33 @@
     expect($requestHeaders['header_testing'][0])->toEqual(123);
 });
 
+test('dbConnectionsChangePassword handles phone_number correctly', function (): void {
+    $clientSecret = uniqid();
+
+    $email = 'someone@somewhere.somehow';
+    $connection = uniqid();
+    $phoneNumber = '+1234567890';
+
+    $this->configuration->setClientSecret($clientSecret);
+    $authentication = $this->sdk->authentication();
+    $authentication->getHttpClient()->mockResponses([HttpResponseGenerator::create()]);
+
+    // Test with phone_number
+    $authentication->dbConnectionsChangePassword($email, $connection, ['phone_number' => $phoneNumber]);
+    $requestWithPhone = $authentication->getHttpClient()->getLastRequest()->getLastRequest();
+    $requestBodyWithPhone = json_decode($requestWithPhone->getBody()->__toString(), true);
+
+    $this->assertArrayHasKey('phone_number', $requestBodyWithPhone);
+    expect($requestBodyWithPhone['phone_number'])->toEqual($phoneNumber);
+
+    // Test without phone_number
+    $authentication->dbConnectionsChangePassword($email, $connection);
+    $requestWithoutPhone = $authentication->getHttpClient()->getLastRequest()->getLastRequest();
+    $requestBodyWithoutPhone = json_decode($requestWithoutPhone->getBody()->__toString(), true);
+
+    $this->assertArrayNotHasKey('phone_number', $requestBodyWithoutPhone);
+});
+
 test('pushedAuthorizationRequest() returns an instance of Auth0\SDK\API\Authentication\PushedAuthorizationRequest', function () {
     $authentication = $this->sdk->authentication();
     $pushedAuthorizationRequest = $authentication->pushedAuthorizationRequest();