Empty categories for green test run

[dimkin-eu]

I'm submitting a ...

• bug report
• feature request
• support request

What is the current behavior?

for green run Categories part is empty

What is the expected behavior?

This part should

• not be displayed
  or
• has some meaningfull message (like disappeared unicorn pic :) )

What is the motivation / use case for changing the behavior?

Seeing empty repo part makes wonder - what happened?

Please tell us about your environment:

• Allure version: 2.1.1
• Test framework: testng@6.8
• Allure adaptor: allure-testng@2.0-BETA8
• Generate report using: allure-maven@2.18

Other information