$app->match('/admin/test1', 'Object::method')->bind('test_url_1')

array(
    'id' => 'item_id',
    'name' => 'Item Name',
    'url' => 'test_url_1'
)

$app->match('/admin/test2/{id}', 'Object::method')->bind('test_url_2')

array(
    'id' => 'item_id',
    'name' => 'Item Name',
    'url' => 'test_url_2'
)

<?php

namespace Plugin\TestPlugin\ServiceProvider;

use Eccube\Application;
use Silex\Application as BaseApplication;
use Silex\ServiceProviderInterface;

class TestPluginServiceProvider implements ServiceProviderInterface
{
    public function register(BaseApplication $app)
    {
        $app->match('/admin/test1', 'Object::method')->bind('test_url_1');
        $app->match('/admin/test2/{id}', 'Object::method')->bind('test_url_2');
        
        $app['config'] = $app->share(
                    $app->extend(
                        'config',
                        function ($config) {
                            // 親アイテム
                            $menuItem['id'] = "parent_item";
                            $menuItem['name'] = "Parent Item";
                            $menuItem['has_child'] = "true";
                            $menuItem['icon'] = "cb-plus-square";
                            
                            // 子供アイテム
                            $children = array(
                                array(
                                    "id" => "child_item_1",
                                    "name" => "Child Item 1",
                                    "url" => "test_url_1" // 成功
                                ),
                                array(
                                    "id" => "child_item_2",
                                    "name" => "Child Item 2",
                                    "url" => "test_url_2"　// 失敗、idが無い
                                )
                            );
                            
                            $menuItem['child'] = $children;

                            $nav = $config['nav'];
                            
                            // 設定アイテムの位置を習得
                            $insertAtIndex = 0;
                            foreach ($nav as $key => $val) {
                                if ($val['id'] == "setting") {
                                    $insertAtIndex = $key;
                                }
                            }
                            
                            // 習得したところの前に入れる
                            array_splice($nav, $insertAtIndex, 0, array($menuItem));
                            
                            // 保存
                            $config['nav'] = $nav;
        
                            return $config;
                        }
                    )
        );
    }
}