fix(android): Avoid ConcurrentModificationException (#1297)

Author: spydon

packages/audioplayers_android/android/src/main/kotlin/xyz/luan/audioplayers/AudioplayersPlugin.kt

@@ -17,6 +17,8 @@ import xyz.luan.audioplayers.player.WrappedPlayer
 import xyz.luan.audioplayers.source.BytesSource
 import xyz.luan.audioplayers.source.UrlSource
 import java.lang.ref.WeakReference
+import java.util.concurrent.ConcurrentHashMap
+import java.util.concurrent.ConcurrentMap
 
 typealias FlutterHandler = (call: MethodCall, response: MethodChannel.Result) -> Unit
 
@@ -27,7 +29,7 @@ class AudioplayersPlugin : FlutterPlugin, IUpdateCallback {
     private lateinit var globalChannel: MethodChannel
     private lateinit var context: Context
 
-    private val players = mutableMapOf<String, WrappedPlayer>()
+    private val players = ConcurrentHashMap<String, WrappedPlayer>()
     private val handler = Handler(Looper.getMainLooper())
     private var updateRunnable: Runnable? = null
 
@@ -189,7 +191,7 @@ class AudioplayersPlugin : FlutterPlugin, IUpdateCallback {
     }
 
     private class UpdateRunnable(
-        mediaPlayers: Map<String, WrappedPlayer>,
+        mediaPlayers: ConcurrentMap<String, WrappedPlayer>,
         channel: MethodChannel,
         handler: Handler,
         updateCallback: IUpdateCallback,