Migrate OkHttpCompat to Kotlin (#51625)

Summary:
Pull Request resolved: #51625

This just migrates this class to Kotlin, which is also the last class in this package.

Changelog:
[Internal] [Changed] -

Reviewed By: rshest

Differential Revision: D75448161

fbshipit-source-id: d5457dd8017fd459d166d2945ff440c303943db2

Author: cortinico

packages/react-native/ReactAndroid/api/ReactAndroid.api

@@ -3025,10 +3025,10 @@ public final class com/facebook/react/modules/network/OkHttpClientProvider {
 	public static final fun setOkHttpClientFactory (Lcom/facebook/react/modules/network/OkHttpClientFactory;)V
 }
 
-public class com/facebook/react/modules/network/OkHttpCompat {
-	public fun <init> ()V
-	public static fun getCookieJarContainer (Lokhttp3/OkHttpClient;)Lcom/facebook/react/modules/network/CookieJarContainer;
-	public static fun getHeadersFromMap (Ljava/util/Map;)Lokhttp3/Headers;
+public final class com/facebook/react/modules/network/OkHttpCompat {
+	public static final field INSTANCE Lcom/facebook/react/modules/network/OkHttpCompat;
+	public final fun getCookieJarContainer (Lokhttp3/OkHttpClient;)Lcom/facebook/react/modules/network/CookieJarContainer;
+	public final fun getHeadersFromMap (Ljava/util/Map;)Lokhttp3/Headers;
 }
 
 public abstract interface class com/facebook/react/modules/network/ProgressListener {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/modules/network/OkHttpCompat.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+@file:Suppress("DEPRECATION_ERROR") // Conflicting okhttp versions
+
+package com.facebook.react.modules.network
+
+import com.facebook.infer.annotation.Nullsafe
+import okhttp3.Headers
+import okhttp3.OkHttpClient
+
+/**
+ * Helper class that provides wrappers for compatibility between different OkHttp versions.
+ *
+ * This is required for Kotlin code compatibility, in particular, therefore if you are going to
+ * migrate this file to Kotlin, please first ensure that there is no OkHttp API discrepancy between
+ * different RN platform environments, and then consider getting rid of this compat layer
+ * altogether.
+ */
+@Nullsafe(Nullsafe.Mode.LOCAL)
+public object OkHttpCompat {
+  public fun getCookieJarContainer(client: OkHttpClient): CookieJarContainer =
+      client.cookieJar() as CookieJarContainer
+
+  public fun getHeadersFromMap(headers: Map<String, String>?): Headers =
+      Headers.of(headers ?: emptyMap())
+}