uid is always updated in previously created dashboards

[ghmeier]

Terraform Version

Terraform v0.12.29
+ provider.grafana v1.8.0 

### Affected Resource(s)
`grafana_dashboard`

### Terraform Configuration Files
```hcl
data "template_file" "grafana-dashboard" {
  template = file("${path.module}/dashboard.json")

  vars = {
    name = var.dashbaord_name
  }
}

resource "grafana_dashboard" "job-queue-dashboard" {
  # "Job queues" folder retrieved from metrics{,-staging}.mixmax.com/api/folders
  folder = "1"

  config_json = data.template_file.grafana-dashboard.rendered
}

Using a dashboard.json file like this:

{
  "annotations": {
    "list": [
      {"builtIn": 1,"datasource": "-- Grafana --","enable": true,"hide": true,"iconColor": "rgba(0, 211, 255, 1)","name": "Annotations and Alerts","type": "dashboard"}
    ]
  },
  "editable": true,
  "gnetId": null,
  "graphTooltip": 0,
  "links": [],
  "panels": [],
  "schemaVersion": 16,
  "style": "dark",
  "tags": [],
  "templating": {"list": []},
  "time": {"from": "now-1h","to": "now"},
  "timepicker": {
    "refresh_intervals": ["5s","10s","30s","1m","5m","15m","30m","1h","2h","1d"],
    "time_options": ["5m","15m","1h","6h","12h","24h","2d","7d","30d"]
  },
  "timezone": "",
  "title": "$name",
  "uid": "$name",
}

Expected Behavior

The dashboard should not reflect changes after the first successful terraform apply

Actual Behavior

The dashboard reflects changes to the uid any time terraform plan is run.

For example (ignoring the whole output of the dashboard file):

      (
           {
                timezone      = ""                                                                                                                                                                                  
                title         = "test"                                                                                                                                             
              ~ uid           = "QiQNwyCik" -> "test"                                                                                                                                     
            }                                                                                                                                                                                                
        )                                                                                                                                                                                                 
        dashboard_id = 27                                                                                                                                                                       
        folder       = 23                                                                                                                                                                       
        id           = "test"                                                                                                                                            
        slug         = "test"                                                                                                                                                         
    }                                                                                                                                                
                                                                                                                                                                                                                             
Plan: 0 to add, 1 to change, 0 to destroy. 

In this case, because uid was set automatically by a version prior to 1.7 we attempt to overwrite the new name, "test", in the updated plan. Even though this plan can be successfully run, it doesn't actually update the uid property on the dashboard.

Steps to Reproduce

1. Set your grafana provider version to 1.7
2. Create a new dashboard with JSON configuration input
3. Upgrade your grafana provider version to 1.8
4. Add the static uid field to your dashboard JSON.
5. Run terraform plan and terraform apply
6. Run terraform plan again and notice changes have been detected.

Important Factoids

This happens with Grafana v5.4.3. I haven't tested newer versions at the moment.

References

I think this PR #136 should probably have detected previous UID state rather than always accepting what's in the dashboard config.

[trotttrotttrott]

@ghmeier thanks for reporting this. I believe this is a duplicate of #151 (which was opened seconds before this). 1.8.1 was just released with a fix.