src/vs/platform/files/common/fileService.ts/FileService/activateProvider
class FileService:	async activateProvider(scheme: string): Promise<void> {

		// Emit an event that we are about to activate a provider with the given scheme.
		// Listeners can participate in the activation by registering a provider for it.
		const joiners: Promise<void>[] = [];
		this._onWillActivateFileSystemProvider.fire({
			scheme,
			join(promise) {
				joiners.push(promise);
			},
		});

		if (this.provider.has(scheme)) {
			return; // provider is already here so we can return directly
		}

		// If the provider is not yet there, make sure to join on the listeners assuming
		// that it takes a bit longer to register the file system provider.
		await Promises.settled(joiners);
	}