method not allowed exception in postmen

I am writing api login register system for my app i have created controller for login and register, i can create my user from postmen and login from there but when i try to call my getdetails method its returning as method not allowed exception here is my Controller

    <?php

namespace App\Http\Controllers\API;

use Illuminate\Http\Request;
use App\Http\Controllers\Controller;
use App\User;
use Illuminate\Support\Facades\Auth;
use Validator;
class PassportController extends Controller
{
//
  public $successStatus = 200;


  public function register(Request $request){
    $validator = Validator::make($request->all(), [
        'name' => 'required',
        'email' => 'required|email',
        'password' => 'required',
        'c_password' => 'required|same:password',
    ]);
    if ($validator->fails()) {
                return response()->json(['error'=>$validator->errors()], 401);            
            }
    $input = $request->all();
    $input['password'] = bcrypt($input['password']);
    $user = User::create($input);

    $success['token'] =  $user->createToken('MyApp')->accessToken;
    $success['name'] =  $user->name;
    return response()->json(['success'=>$success], $this->successStatus);
}

public function login(){
    if(Auth::attempt(['email' => request('email'), 'password' => request('password')])){

        $user = Auth::user();
        $success['token'] =  $user->createToken('MyApp')->accessToken;
        return response()->json(['success' => $success], $this->successStatus);
    }
    else{
        return response()->json(['error'=>'Unauthorised'], 401);
    }
}


public function getDetails()
{
    $user = Auth::user();
    return response()->json(['success' => $user], $this->successStatus);
}

}

api.php

 <?php

use Illuminate\Http\Request;

/*
|--------------------------------------------------------------------------
| API Routes
|--------------------------------------------------------------------------
|
| Here is where you can register API routes for your application. These
| routes are loaded by the RouteServiceProvider within a group which
| is assigned the "api" middleware group. Enjoy building your API!
|
*/

Route::middleware('auth:api')->get('/user', function (Request $request) {
    return $request->user();
});

Route::post('register', 'API\PassportController@register')->name('register');
Route::post('login', 'API\PassportController@login')->name('login');



Route::group(['middleware' => 'auth:api'], function(){
 Route::post('details', 'API\PassportController@getDetails');
});

here is my postmen screenshot

via Chebli Mohamed