src/vs/platform/extensionManagement/common/extensionGalleryService.ts/ExtensionGalleryService/getManifest
class ExtensionGalleryService:	async getManifest(extension: IGalleryExtension, token: CancellationToken): Promise<IExtensionManifest | null> {
		if (extension.assets.manifest) {
			const context = await this.getAsset(extension.assets.manifest, {}, token);
			const text = await asText(context);
			return text ? JSON.parse(text) : null;
		}
		return null;
	}