src/vs/platform/policy/common/filePolicyService.ts/FilePolicyService/read
class FilePolicyService:	private async read(): Promise<Map<PolicyName, PolicyValue>> {
		const policies = new Map<PolicyName, PolicyValue>();

		try {
			const content = await this.fileService.readFile(this.file);
			const raw = JSON.parse(content.value.toString());

			if (!isObject(raw)) {
				throw new Error('Policy file isn\'t a JSON object');
			}

			for (const key of Object.keys(raw)) {
				if (this.policyDefinitions[key]) {
					policies.set(key, raw[key]);
				}
			}
		} catch (error) {
			if ((<FileOperationError>error).fileOperationResult !== FileOperationResult.FILE_NOT_FOUND) {
				this.logService.error(`[FilePolicyService] Failed to read policies`, error);
			}
		}

		return policies;
	}