Error: "kamer" plugin is not implemented on android

Ionic Framework Ionic Vue
1

I am trying to test native custom codes. So I read documentation and tried to test it.
I tried everything as possible. But eventually it says Error: “kamer” plugin is not implemented on android.
My Android camera.java

package com.ionic.multi;

import com.getcapacitor.JSObject;
import com.getcapacitor.Plugin;
import com.getcapacitor.PluginCall;
import com.getcapacitor.PluginMethod;
import com.getcapacitor.annotation.CapacitorPlugin;

@CapacitorPlugin(name = “kamer”)
public class camera extends Plugin {

@PluginMethod()
public void echo(PluginCall call) {
    String value = call.getString("value");

    JSObject ret = new JSObject();
    ret.put("value", value);
    call.resolve(ret);
}

}
my MainActivity.class
package com.ionic.multi;
import android.os.Bundle;
import com.getcapacitor.BridgeActivity;

public class MainActivity extends BridgeActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
registerPlugin(com.ionic.multi.camera.class);
super.onCreate(savedInstanceState);
}
}
my vuejs ts
import { registerPlugin } from ‘@capacitor/core’;

const MultiCamera = registerPlugin(‘kamer’);

export default MultiCamera;