feat: Add optional state parameter to AuthorizationCode and update PARCodeManager to handle it

Author: subhankarmaiti

auth0/src/main/java/com/auth0/android/provider/PARCodeManager.kt

@@ -27,6 +27,7 @@ internal class PARCodeManager(
         private const val KEY_CLIENT_ID = "client_id"
         private const val KEY_REQUEST_URI = "request_uri"
         private const val KEY_CODE = "code"
+        private const val KEY_STATE = "state"
         private const val KEY_ERROR = "error"
         private const val KEY_ERROR_DESCRIPTION = "error_description"
         private const val ERROR_VALUE_ACCESS_DENIED = "access_denied"
@@ -81,8 +82,11 @@ internal class PARCodeManager(
             return true
         }
 
-        // Success - return authorization code
-        val authorizationCode = AuthorizationCode(code = code)
+        // Extract optional state
+        val state = values[KEY_STATE]
+
+        // Success - return authorization code with optional state
+        val authorizationCode = AuthorizationCode(code = code, state = state)
         callback.onSuccess(authorizationCode)
         return true
     }

auth0/src/main/java/com/auth0/android/result/AuthorizationCode.kt

@@ -6,11 +6,18 @@ package com.auth0.android.result
  * handles the token exchange.
  *
  * @property code The authorization code from the callback
+ * @property state The optional state parameter from the callback, if present
  */
 public data class AuthorizationCode(
     /**
      * The authorization code received from Auth0.
      * This code should be sent to your BFF for token exchange.
      */
-    public val code: String
+    public val code: String,
+
+    /**
+     * The optional state parameter received from Auth0.
+     * This can be used by the BFF to correlate the response with the original request.
+     */
+    public val state: String? = null
 )