aws_events.Rule doesn't accept aws_events_targets.SfnStateMachine as a target

When trying to add a target to an event in Python, following error is produced on synth:

Error: Resolution error: Supplied properties not correct for "CfnRuleProps"
  targets: element 0: supplied properties not correct for "TargetProperty"
    arn: required but missing.

Rule is aws_events.Rule object, and target is aws_events_targets.SfnStateMachine.

Reproduction Steps

event = aws_events.Rule(
            self,
            id="Scheduled event",
            enabled=True,
            schedule=aws_events.Schedule.expression(app_config["event_schedule"])
)
event.add_target(aws_events_targets.SfnStateMachine(machine=state_machine))

Error Log

/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/resolvable.js:51
            throw e;
            ^

Error: Resolution error: Supplied properties not correct for "CfnRuleProps"
  targets: element 0: supplied properties not correct for "TargetProperty"
    arn: required but missing.
Object creation stack:
  at new Intrinsic (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/private/intrinsic.js:20:44)
  at new PostResolveToken (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/util.js:72:9)
  at CfnRule._toCloudFormation (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/cfn-resource.js:167:39)
  at elements.map.e (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/stack.js:547:60)
  at Array.map (<anonymous>)
  at Stack._toCloudFormation (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/stack.js:547:36)
  at Stack.synthesize (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/stack.js:500:42)
  at Function.synth (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/construct.js:65:27)
  at App.synth (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/app.js:71:52)
  at process.App.process.once (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/app.js:45:51)
  at Object.onceWrapper (events.js:286:20)
  at process.emit (events.js:198:13)
    at ValidationResult.assertSuccess (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/runtime.js:126:19)
    at cfnRulePropsToCloudFormation (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/aws-events/lib/events.generated.js:165:39)
    at CfnRule.renderProperties (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/aws-events/lib/events.generated.js:214:16)
    at PostResolveToken.ret.Resources.util_1.PostResolveToken.props [as processor] (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/cfn-resource.js:178:52)
    at PostResolveToken.postProcess (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/util.js:80:21)
    at Object.postProcess (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/private/resolve.js:30:82)
    at DefaultTokenResolver.resolveToken (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/resolvable.js:42:38)
    at resolve (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/private/resolve.js:94:33)
    at Object.resolve (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/private/resolve.js:28:33)
    at resolve (/tmp/jsii-kernel-8Mu6hw/node_modules/@aws-cdk/core/lib/private/resolve.js:111:43)

Environment

• CLI Version : 1.13.1 (build 96cfc63)
• Framework Version: 1.13.1
• OS : Fedora
• Language : Python

Other

This happens in all following cases:

• By supplying targets keyword in rule constructor
• By using add_target() on rule object
• By using bind(rule_obj) on target object

I also checked target type LambdaFunction, but it works (aside from type mismatch, target is based on object instead of implementing IRuleTarget expected by rule object)

---

This is 🐛 Bug Report

[oleksii-donoha]

@SomayaB I might be out of the loop, but shouldn’t label “package/events” be more appropriate?

[raajheshkannaa]

The same error happens with having codepipeline as a target for an event as well.

jsii.errors.JavaScriptError: 
  Error: Resolution error: Supplied properties not correct for "CfnRuleProps"
    targets: element 0: supplied properties not correct for "TargetProperty"
      arn: required but missing.

below is the code

		repo = codecommit.Repository(
			self, 'Repository',
			repository_name='Repository'
		)

		source_artifact = codepipeline.Artifact()

		cloud_assembly_artifact = codepipeline.Artifact()

		pipeline = CodePipeline(self, 'Pipeline',
			synth=ShellStep("Synth",
			input=CodePipelineSource.code_commit(
				repository=repo,
				branch='master'),
			commands=[
				'pip install -r requirements', 
				'npm install -g aws-cdk', 
				'cdk synth']
			)
			)

		rule = events.Rule(self, 'TriggerPipeline',
			schedule=events.Schedule.expression('rate(1 hour)')
		)

		rule.add_target(targets.CodePipeline(pipeline))