src/vs/workbench/contrib/extensions/browser/extensionsActions.ts/InstallSpecificVersionOfExtensionAction/isEnabled
class InstallSpecificVersionOfExtensionAction:	private isEnabled(extension: IExtension): boolean {
		const action = this.instantiationService.createInstance(InstallAnotherVersionAction);
		action.extension = extension;
		return action.enabled && !!extension.local && this.extensionEnablementService.isEnabled(extension.local);
	}