[cronet_http] Fix ClassNotFoundException in debug mode (#1840)

* [cronet_http] Fix `ClassNotFoundException` in debug mode

* Update changelog

Author: HosseinYousefi

pkgs/cronet_http/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.6.1-wip
+
+* Fix a bug where cronet would throw `ClassNotFoundException` in debug mode.
+
 ## 1.6.0
 
 * Upgrade the `cronet-embedded` dependency to `141.7340` version to

pkgs/cronet_http/android/src/main/kotlin/io/flutter/plugins/cronet_http/UrlRequestCallbackProxy.kt

@@ -14,6 +14,7 @@
 
 package io.flutter.plugins.cronet_http
 
+import androidx.annotation.Keep
 import org.chromium.net.CronetException
 import org.chromium.net.UrlRequest
 import org.chromium.net.UrlResponseInfo
@@ -31,8 +32,10 @@ import java.nio.ByteBuffer
 // parameter is nullable as specified in the cronet source code:
 // https://source.chromium.org/chromium/chromium/src/+/main:components/cronet/android/api/src/org/chromium/net/UrlRequest.java;l=232
 
+@Keep
 class UrlRequestCallbackProxy(val callback: UrlRequestCallbackInterface) : UrlRequest.Callback() {
-    public interface UrlRequestCallbackInterface {
+    @Keep
+    interface UrlRequestCallbackInterface {
         fun onRedirectReceived(
             request: UrlRequest?,
             info: UrlResponseInfo?,

pkgs/cronet_http/pubspec.yaml

@@ -1,5 +1,5 @@
 name: cronet_http
-version: 1.6.0
+version: 1.6.1-wip
 description: >-
   An Android Flutter plugin that provides access to the Cronet HTTP client.
 repository: https://github.com/dart-lang/http/tree/master/pkgs/cronet_http