"clientId must be a non empty string" error from task when using Managed Service Authentication

[Philo]

I am trying to ARM Outputs from a release pipeline that is using a service connection configured using the "Managed Identity Authentication". This means I have a private agent VM in Azure with MSI configured through which ARM permissions are set.

This is working as expected for the App Deploy tasks but when I add the ARM Outputs trask I get the following error.

2019-02-20T13:30:54.3420341Z ##[section]Starting: ARM Outputs
2019-02-20T13:30:54.3424062Z ==============================================================================
2019-02-20T13:30:54.3424120Z Task         : ARM Outputs
2019-02-20T13:30:54.3424174Z Description  : This task reads the output values of an ARM deployment and sets them as Azure Pipelines variables.
2019-02-20T13:30:54.3424213Z Version      : 5.0.20
2019-02-20T13:30:54.3424246Z Author       : Kees Schollaart
2019-02-20T13:30:54.3424280Z Help         : [More Information](https://github.com/keesschollaart81/vsts-arm-outputs)
2019-02-20T13:30:54.3424335Z ==============================================================================
2019-02-20T13:30:55.2671459Z bdd875f9-d4da-4d9e-b981-3993745a5aef exists true
2019-02-20T13:30:55.2690192Z Unhandled exception during ARM Outputs Task Error: clientId must be a non empty string.
2019-02-20T13:30:55.2690596Z     at new ApplicationTokenCredentials (webpack://someLibName/./node_modules/ms-rest-azure/lib/credentials/applicationTokenCredentials.js?:75:13)
2019-02-20T13:30:55.2691108Z     at AzureDevOpsArmOutputsTaskHost.getCredentials (webpack://someLibName/./dist/index.js?:81:31)
2019-02-20T13:30:55.2691321Z     at AzureDevOpsArmOutputsTaskHost.eval (webpack://someLibName/./dist/index.js?:24:40)
2019-02-20T13:30:55.2691493Z     at next (native)
2019-02-20T13:30:55.2691640Z     at eval (webpack://someLibName/./dist/index.js?:7:71)
2019-02-20T13:30:55.2691786Z     at __awaiter (webpack://someLibName/./dist/index.js?:3:12)
2019-02-20T13:30:55.2692108Z     at AzureDevOpsArmOutputsTaskHost.run (webpack://someLibName/./dist/index.js?:18:26)
2019-02-20T13:30:55.2692254Z     at eval (webpack://someLibName/./dist/index.js?:88:31)
2019-02-20T13:30:55.2692386Z     at Object../dist/index.js (C:\agent\_work\_tasks\ARM Outputs_584bcff2-3353-4f11-872b-6ba01267a972\5.0.20\index.js:131:1)
2019-02-20T13:30:55.2692555Z     at __webpack_require__ (C:\agent\_work\_tasks\ARM Outputs_584bcff2-3353-4f11-872b-6ba01267a972\5.0.20\index.js:30:30)
2019-02-20T13:30:55.2840988Z ##[error]Error: clientId must be a non empty string.
2019-02-20T13:30:55.7707236Z ##[section]Finishing: ARM Outputs

I can only assume that this form of endpoint/ARM authentication is not currently supported by the task? If this is the case would be be possible to support this type of service connection in a future update?

[Philo]

Thanks for the feature inclusion 👍