How to create Snap for a simple Qt5 app?

My yaml-file is as follows:

name: heimer
version: '1.0.0'
summary: Heimer is a simple cross-platform mind map tool.
description: |
  Heimer is a simple cross-platform mind map creation tool.
  Emphasis on easy diagram creation, simplicity, and speed.
grade: stable
confinement: strict

    command: desktop-launch heimer
      - home

    source: ../
    plugin: cmake
      - libc6
    after: [desktop-qt5]

When I build it ends up with this:

'libc6' is required inside the snap for this part to work properly.
Add it as a `stage-packages` entry for this part.

Now what? I already have listed it in “stage-packages”. I’ve tried also without this after: [desktop-qt5] magic, but then I got runtime errors about Qt’s XCB platform plugin I couldn’t solve.

Ok, I found out that I this doesn’t work on 18.04 and I need to run this under 16.04 instead due to current snap core version.