refactor: Apply suggestion from code review

Author: NicolasBourdin88

Network/Models/src/main/java/com/infomaniak/core/network/models/ApiResponse.kt

@@ -49,7 +49,7 @@ open class ApiResponse<T>(
     val itemsPerPage: Int = 0,
 ) {
     @Transient
-    var headers: InfomaniakHeaders? = null
+    var headers: ResponseHeaders? = null
 
     fun isSuccess() = result == ApiResponseStatus.SUCCESS
 }

Network/Models/src/main/java/com/infomaniak/core/network/models/InfomaniakHeaders.kt

@@ -0,0 +1,41 @@
+/*
+ * Infomaniak Core - Android
+ * Copyright (C) 2025 Infomaniak Network SA
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see http://www.gnu.org/licenses/.
+ */
+package com.infomaniak.core.network.models
+
+import okhttp3.Headers
+import kotlin.reflect.KProperty
+
+class ResponseHeaders(headers: Headers) {
+    private val headersBacking = HeadersBacking(headers)
+
+    val lastModified: String? by headersBacking.header("last-modified")
+}
+
+private class HeadersBacking(val remoteHeaders: Headers) {
+    fun header(key: String): HeaderData {
+        return object : HeaderData {
+            override fun getValue(thisRef: Any?, property: KProperty<*>): String? {
+                return remoteHeaders[key]
+            }
+        }
+    }
+}
+
+private interface HeaderData {
+    operator fun getValue(thisRef: Any?, property: KProperty<*>): String?
+}

Network/Models/src/main/java/com/infomaniak/core/network/models/ResponseHeaders.kt

@@ -26,7 +26,7 @@ import com.infomaniak.core.network.isSerializationException
 import com.infomaniak.core.network.models.ApiError
 import com.infomaniak.core.network.models.ApiResponse
 import com.infomaniak.core.network.models.ApiResponseStatus
-import com.infomaniak.core.network.models.InfomaniakHeaders
+import com.infomaniak.core.network.models.ResponseHeaders
 import com.infomaniak.core.network.models.exceptions.NetworkException
 import com.infomaniak.core.network.models.exceptions.ServerErrorException
 import com.infomaniak.core.network.networking.HttpClient
@@ -187,7 +187,7 @@ object ApiController {
             @Suppress("DEPRECATION")
             apiResponse.translatedError = InternalTranslatedErrorCode.UnknownError.translateRes
         }
-        if (apiResponse is ApiResponse<*>) apiResponse.headers = InfomaniakHeaders(headers)
+        if (apiResponse is ApiResponse<*>) apiResponse.headers = ResponseHeaders(headers)
 
         return apiResponse
     }