Template with default functionality of Java classes for making fragmented plugins on Unity

PluginFragment.class

package com.eric.nativetoolkit;

import android.app.Fragment;
import android.os.Bundle;
import android.util.Log;

import com.unity3d.player.UnityPlayer;

import androidx.annotation.Nullable;

public class NativeToolkitFragment extends Fragment
{
    //Tag to follow logcats
    private static final String TAG = "NativeToolkit";
    // Singleton instance.
    public static NativeToolkitFragment instance;

    //UNITY CONTEXT
    String gameObjectName;
    String resultCallbackName = "OnResult";
    public static void SendUnityResults(String results)
    {
        UnityPlayer.UnitySendMessage(instance.gameObjectName, instance.resultCallbackName, results);
        Log.d(TAG, results);
    }
    public static void SetUp(String gameObjectName)
    {
        instance = new NativeToolkitFragment();
        instance.gameObjectName = gameObjectName; // Store 'GameObject' reference
        UnityPlayer.currentActivity.getFragmentManager().beginTransaction().add(instance, NativeToolkitFragment.TAG).commit();
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setRetainInstance(true);
    }

    public static String getMessage()
    {
        return "Hello World!";
    }
}