publishToConfluence fails when no hash is available for an uploaded image

[Rosi2143]

Describe the bug
If an image is part of the confluence page that has - for yet unknown reasons - no hash attached the task publischToConfluence fails with an error that replaceAll() is not working on "null"

To Reproduce
Unfortunately -> no idea. We had a manually created confluence page where a single picture had no hash.

Expected behavior
Tupload shall still succeed by replacing the existing image with the new one.

Configuration

• docToolchain version: 2.0.3
• OS: [e.g. Windows, Linux, ...] Linux / Ubuntu 20.4
• Browser [e.g. chrome, safari] Firefox
• Relevant SDK Versions [e.g. JDK 1.8, ...]

[Rosi2143]

Closed with #711