@W-20161958: [MSDK 13.1][Android] Cannot login GUS using Welcome endpoint

Author: JohnsonEricAtSalesforce

libs/SalesforceSDK/src/com/salesforce/androidsdk/ui/LoginActivity.kt

@@ -173,6 +173,8 @@ import java.security.cert.X509Certificate
  * them.
  */
 open class LoginActivity : FragmentActivity() {
+    private var customTabLauncher: ActivityResultLauncher<Intent>? = null
+
     // View Model
     @VisibleForTesting(otherwise = PROTECTED)
     open val viewModel: LoginViewModel
@@ -270,7 +272,7 @@ open class LoginActivity : FragmentActivity() {
             onBackPressedDispatcher.addCallback { handleBackBehavior() }
         }
 
-        val customTabLauncher: ActivityResultLauncher<Intent> = registerForActivityResult(
+        customTabLauncher = registerForActivityResult(
             ActivityResultContracts.StartActivityForResult()
         ) { result: ActivityResult ->
             // Check if the user backed out of the custom tab.
@@ -285,48 +287,6 @@ open class LoginActivity : FragmentActivity() {
             }
         }
 
-        // Take action on selected server change.
-        viewModel.selectedServer.observe(this) { selectedServer ->
-
-            // Guard against observing a selected server already provided by the intent data, such as a Salesforce Welcome Discovery mobile URL.
-            val selectedServerUri = selectedServer.toUri()
-            if (intent.data?.host == selectedServerUri.host) {
-                return@observe
-            }
-
-            // Use the URL to switch between default or Salesforce Welcome Discovery log in, if applicable.
-            if (switchDefaultOrSalesforceWelcomeDiscoveryLogin(selectedServerUri)) {
-                return@observe
-            }
-
-            if (viewModel.singleServerCustomTabActivity) {
-                // Skip fetching authorization and show custom tab immediately.
-                viewModel.reloadWebView()
-                viewModel.loginUrl.value?.let { url ->
-                    loadLoginPageInCustomTab(url, customTabLauncher)
-                }
-            } else {
-                with(SalesforceSDKManager.getInstance()) {
-                    // Fetch well known config and load in custom tab if required.
-                    fetchAuthenticationConfiguration {
-                        /* Browser-based authentication is applicable when not authenticating with a front-door bridge URL */
-                        if (isBrowserLoginEnabled && !viewModel.isUsingFrontDoorBridge) {
-                            if (useWebServerAuthentication) {
-                                viewModel.loginUrl.value?.let { url -> loadLoginPageInCustomTab(url, customTabLauncher) }
-                            } else {
-                                /* Reload the webview now that isBrowserLoginEnabled has been set
-                                   to true so that we generate an authorization URL with PKCE values.  */
-                                lifecycleScope.launch(Dispatchers.Main) {
-                                    viewModel.reloadWebView()
-                                    viewModel.loginUrl.value?.let { url -> loadLoginPageInCustomTab(url, customTabLauncher) }
-                                }
-                            }
-                        }
-                    }
-                }
-            }
-        }
-
         // Support magic links
         if (viewModel.jwt != null) {
             swapJWTForAccessToken()
@@ -1097,6 +1057,59 @@ open class LoginActivity : FragmentActivity() {
 
         // If the intent is for log in using a UI Bridge API front door URL, apply it to the activity.
         applyUiBridgeApiFrontDoorUrl(intent)
+
+        applySelectedServer()
+    }
+
+    /**
+     * Applies the view model's selected server to the activity.
+     */
+    private fun applySelectedServer() {
+
+        // Reset the selected login server observer to consume the latest and future values.
+        viewModel.selectedServer.removeObservers(this)
+        viewModel.selectedServer.observe(this) { selectedServer ->
+
+            // Guard against observing a selected server already provided by the intent data, such as a Salesforce Welcome Discovery mobile URL.
+            val selectedServerUri = selectedServer.toUri()
+            if (intent.data?.host == selectedServerUri.host) {
+                return@observe
+            }
+
+            // Use the URL to switch between default or Salesforce Welcome Discovery log in, if applicable.
+            if (switchDefaultOrSalesforceWelcomeDiscoveryLogin(selectedServerUri)) {
+                return@observe
+            }
+
+            if (viewModel.singleServerCustomTabActivity) {
+                // Skip fetching authorization and show custom tab immediately.
+                viewModel.reloadWebView()
+                viewModel.loginUrl.value?.let { url ->
+                    customTabLauncher?.let { loadLoginPageInCustomTab(url, it) }
+                }
+            } else {
+                with(SalesforceSDKManager.getInstance()) {
+                    // Fetch well known config and load in custom tab if required.
+                    fetchAuthenticationConfiguration {
+                        /* Browser-based authentication is applicable when not authenticating with a front-door bridge URL */
+                        if (isBrowserLoginEnabled && !viewModel.isUsingFrontDoorBridge) {
+                            if (useWebServerAuthentication) {
+                                viewModel.loginUrl.value?.let { url ->
+                                    customTabLauncher?.let { loadLoginPageInCustomTab(url, it) }
+                                }
+                            } else {
+                                /* Reload the webview now that isBrowserLoginEnabled has been set
+                                   to true so that we generate an authorization URL with PKCE values.  */
+                                lifecycleScope.launch(Dispatchers.Main) {
+                                    viewModel.reloadWebView()
+                                    viewModel.loginUrl.value?.let { url -> customTabLauncher?.let { loadLoginPageInCustomTab(url, it) } }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
     }
 
     /**