StateTransitionReason has no value after stopping an instance

[otufekci]

Hi All,

I am struggling with getting moto 5.0.3 test run correctly. I have a code that reads StateTransitionReason date and makes calculations to find the difference. However, after stopping instance with moto:

    reservation = ec2.create_instances(
        ImageId=EXAMPLE_AMI_ID, 
        MinCount=1, 
        MaxCount=1,
        TagSpecifications=[
            {
                "ResourceType": "instance",
                "Tags": ec2_tags,
            }
        ]
    )

    # stop instances
    reservation[0].stop()

Field for the StateTransitionReason turns empty.

'State': {'Code': 80, 'Name': 'stopped'}, 
'StateTransitionReason': '', 
'SubnetId': 'subnet-b4e251ec'

I am expecting to see similar result to documentation.

'StateTransitionReason': 'User initiated (2019-04-08 14:29:07 UTC)',

Thank you for your help in advance...