magento2: Parent menu not shown when there's only 1 submenu in admin panel

Preconditions

1. Magento EE 2.2.1 & Magento EE 2.2.2

Steps to reproduce

1. Create a module

2. Create a new file menu.xml in folder adminhtml

3. Create new menu like this `

   <add id="Footballexperience_Base::base" title="FExperience" module="Footballexperience_Base" sortOrder="20" resource="Magento_Customer::customer"/>

    <add id="Footballexperience_Base::manage_stadiums"
         title="Manage Stadiums"
         module="Footballexperience_Base"
         sortOrder="10"
         parent="Footballexperience_Base::base"
         resource="Footballexperience_Base::manage_stadiums"
    />
   
    <add id="Footballexperience_Base::stadiums"
         title="Stadiums"
         module="Footballexperience_Base"
         sortOrder="10"
         resource="Footballexperience_Base::stadiums"
         parent="Footballexperience_Base::manage_stadiums"
         action="febase/stadium/grid"
    />
   

`

Repository test

https://github.com/hi-rafa/magento2test221

Expected result

When you click the new menu added you should see inside a submenu like this Manage Stadiums -> Stadiums

Actual result

What you actually see is only the menu Stadiums unless you add more than one submenu.

Additional information

If you add 2 submenus it will work