src/vs/platform/workspace/common/workspace.ts/Workspace/getFolder
class Workspace:	getFolder(resource: URI): IWorkspaceFolder | null {
		if (!resource) {
			return null;
		}

		return this._foldersMap.findSubstr(resource.with({
			scheme: resource.scheme,
			authority: resource.authority,
			path: resource.path
		})) || null;
	}