ECS Management API: Create user with tags fails

Hey,

I try to create a user with tags following this documentation:

https://www.emc.com/techpubs/api/ecs/v2-2-0-0/UserManagementService_addUser_4ded29bfad3eccbd28fb5b1f666c8f44_b2081f90369a6d96de7811240fd3b244_detail.htm

But this always fails.

I send my query against: ecsnode:4443/object/users.json

JSON Body

{
  "user": "newuser",
  "namespace": "namespace",
  "tags": [
    "bla"
  ]
}

This is what i get:

{
    "code": 1013,
    "retryable": false,
    "description": "Bad request body",
    "details": "Can not instantiate value of type [simple type, class com.emc.storageos.data.datasvcmodels.user.UserTagParam] from JSON String; no single-String constructor/factory method (through reference chain: com.emc.storageos.data.datasvcmodels.user.UserCreateParam[\"tags\"])"
}

Any ideas what i may do wrong?

Thanks

Thomas