Add 'onStartupFinished' event to the list of supported activation events

[vinokurig]

Signed-off-by: Igor Vinokur ivinokur@redhat.com

What it does

Add 'onStartupFinished' event to the list of supported activation events

This fixes an issue which is mentioned here #8525 (comment)

How to test

1. Clone any Theia plugin e.g https://github.com/eclipse/che-theia-samples/tree/master/samples/hello-world-backend-plugin
2. Change the activation event in its package.json from * to onStartupFinished
3. Start the plugin.
4. See: root ERROR [hosted-plugin: 93564] Unsupported activation events: onStartupFinished, please open an issue: https://github.com/eclipse-theia/theia/issues/new console error is gone.

Review checklist

• as an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the review guidelines

[tsmaeder]

While this fixes the immediate problem, it would be good to make the possible activation events its own type (string union or enum) in order make the compiler complain when we use something that is not supported. Not in this PR maybe, but as a separate refactoring.

[RomanNikitenko]

If I understand correctly - the support for the onStartupFinished activation event was added within #8525.
The current PR is only adding the onStartupFinished event to the list of supported events.

Tested using the How to test section - I don't see the error in my console and I'm able to use Hello World command from the sample plugin.

[vinokurig]

@RomanNikitenko Right, this PR just registers the previously added onStartupFinished activation event as a known one. Thanks for the review!

[RomanNikitenko]

@vinokurig
please remove the branch if it's not used anymore

thanks!