src/vs/workbench/api/common/extHostExtensionActivator.ts/ExtensionsActivator/activateByEvent
class ExtensionsActivator:	public async activateByEvent(activationEvent: string, startup: boolean): Promise<void> {
		if (this._alreadyActivatedEvents[activationEvent]) {
			return;
		}

		const activateExtensions = this._registry.getExtensionDescriptionsForActivationEvent(activationEvent);
		await this._activateExtensions(activateExtensions.map(e => ({
			id: e.identifier,
			reason: { startup, extensionId: e.identifier, activationEvent }
		})));

		this._alreadyActivatedEvents[activationEvent] = true;
	}