Add menu to the explorer view

Question

Isn't it possible to add a new menu item for explorer view ? Right click on the project I want to add a new menu item.

If I contribute to the explorer/context menu it gets added but it appears only when I right click on files inside the project.

  "commands": [
  {
      "command": "extension.Upgrade",
      "title": "My Menu"
  }
],
  "menus": {
    "explorer/context": [{
        "command": "extension.Upgrade",
        "group": "navigation"

  }]
}