Exposed the metadata scanner to the API.

[kittaakos]

So extensions developer can subclass the hoster plugin reader.

Signed-off-by: Akos Kitta [email protected]

What it does

Sets the MetadataScanner (scanner) visibility from private to protected.

How to test

Review the change set on GH.

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

[kittaakos]

I found another issue with the HosterPluginReader. It implements the BackendApplicationContribution but no-one binds it, so subclasses cannot do much with onStart.

I fix this withing this PR.
Update: I was wrong.

[benoitf]

would be interesting to know why you need to subclass ?

[kittaakos]

would be interesting to know why you need to subclass ?

No secret: I am trying to add a schema on the fly to the redhat YAML VS Code extension without creating or modifying the user or workspace settings.

Here: https://github.com/redhat-developer/vscode-yaml/blob/5e339a44a46aceb48ed2aedabc3146ab5db63559/package.json#L85

[benoitf]

You may use another VS Code extension like

https://github.com/Azure/vscode-kubernetes-tools/blob/16ee367c0943097abee7ad098f3907f9663ef8b8/src/yaml-support/yaml-schema.ts#L30-L36