Allow extra properties in .code-workspace files

[OmarTawfik]

I'm looking into using .code-workspace files for many projects in the same codebase. One thing that is blocking us right now is that we cannot add extra info or metadata to these JSONP files, because of this validation:

vscode/src/vs/workbench/api/common/configurationExtensionPoint.ts

Line 318 in d832f86

errorMessage: nls.localize('unknownWorkspaceProperty', "Unknown workspace configuration property")

The ability to add extra data in this file for our build system to use is crucial, as it will enable us to attach build/project settings to these workspaces, and make maintaining it much easier moving forward.

VSCode has been great in its extensibility model in other features, so here I propose adding another extension point $metadata to this file, where others can add whatever they want in that object:

{
  "folders": [
  ],
  "settings: {
  },
  "$metadata": {
  }
}

• The name can be changed. $metadata is just a placeholder :) not sure about the convention in other places in VSCode.
• The new field is optional.
• Is a JSON object.
• Can contain arbitrary properties/fields.

I can submit a PR to change the validation in the file above, if the VSCode team approves.

[bpasero]

//cc @aeschli @sandy081 not sure why we would not relax this condition

[andekande]

Can't the same be achieved by moving custom properties into the settings object ?
Something like "properties": { "build": { "propA": "value" } }

Then I would assume I can access them, for example in the tasks section like ${settings:properties:build:propA}

Please clarify how your build scripts would access these properties. When you parse the file by yourself anyways, then why not put an additional config file next to the .code-workspace which gives you full control over its syntax.

[sandy081]

settings object already accepts additional properties.