MainActivity.kt：（12，48）：类型不匹配：推断的类型是MainActivity，但应为FlutterEngine

Question

我正在尝试编写一些特定于平台的代码，但遇到了问题。但是运行不顺，我无法解决此问题，请共享代码。

package com.thegosai.theknowledge
import android.os.Bundle
import io.flutter.app.FlutterActivity
import io.flutter.plugins.GeneratedPluginRegistrant
import io.flutter.plugin.common.MethodChannel
class MainActivity : FlutterActivity() {
    private val CHANNEL = "samples.flutter.dev/autostart"
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        GeneratedPluginRegistrant.registerWith(this);
         MethodChannel(flutterView, CHANNEL).setMethodCallHandler { call, result ->
            if (call.method == "getmanufacture") {
                val s = getmanufacture();
                result.success(s);
            } else {
                result.notImplemented();
            }
        }
    }
    private fun getmanufacture(): String {
        val manufacturer: String = android.os.Build.MANUFACTURER;
        return manufacturer;
    }
}