Metric will not update CloudFormation for changed unit

[sbstjn]

If you change a Metric unit in a CloudWatch Dashboard/Widget, the aws-cdk will not generate new CloudFormation resources when title is changed.

Reproduction Steps

First, deploy the dashboard with a widget and metric, then change the metric's unit and deploy again.

dashboard.addWidgets(
  new GraphWidget({
    title: 'A: B',
    width: 12,
    left: [
      new Metric({
        label: 'Duration',
        metricName: 'Duration',
        statistic: 'Average',
        // unit: Unit.MILLISECONDS,
        namespace: 'AWS/Lambda',
        dimensions: {
          FunctionName: foo.functionName
        }
      })
    ]
  })
)

Environment

• CLI Version : 1.14.0
• Framework Version: 1.14.0
• OS :
• Language : TypeScript

Other

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This is 🐛 Bug Report

[nmussy]

Hey @sbstjn,

You're not seeing any changes because the unit property isn't set. As you can see in the CloudWatch API Rerefernce, there is no corresponding key. I assume that the CloudWatch Dashboard just uses the reported metric unit.

We could create a new WidgetMetric type to prevent future confusion. Thoughts?