extraneous key [HealthCheck] is not permitted - aws-cloudformation

Question

I'm kinda stuck with this weird error.
I'm deploying an ECS Task (Fargate) using a CloudFormation script, it works and successfully deploy the Task. But when the HealthCheck property is set Cloudformation replies
Resource handler returned message: "Model validation failed (#: extraneous key [HealthCheck] is not permitted)" (RequestToken: xxxxxxx-xxx-xxxx-xxxx-xxxxxxxxxxxx, HandlerErrorCode: InvalidRequest)
and my task definition is :
TaskDefinition:
Type: AWS::ECS::TaskDefinition
Properties:
Family: !Sub ${ServiceName}-${EnvironmentName}
Cpu: !Ref 'ContainerCpu'
Memory: !Ref 'ContainerMemory'
NetworkMode: awsvpc
RequiresCompatibilities:
- FARGATE
ExecutionRoleArn: arn:aws:iam::xxxxxxxx:role/some-iam-role
HealthCheck:
Command:
- [ CMD-SHELL,./compose/healthcheck.sh || exit 1 ]
Interval: 10
Retries: 5
StartPeriod: 30
Timeout: 5
TaskRoleArn:
Fn::If:
- 'HasCustomRole'
- !Ref 'Role'
- !Ref "AWS::NoValue"
ContainerDefinitions:
- Name: !Ref 'ServiceName'
Cpu: !Ref 'ContainerCpu'
Memory: !Ref 'ContainerMemory'
Image: !Ref 'ImageUrl'
PortMappings:
- ContainerPort: !Ref 'ContainerPort'
LogConfiguration:
LogDriver: 'awslogs'
Options:
awslogs-group: !Sub ${ServiceName}-service-${EnvironmentName}
awslogs-region: !Ref 'AWS::Region'
awslogs-stream-prefix: !Ref 'ServiceName'
Environment:
- <some other environment that work ok>

Answer 1

HealthCheck is a sub-property of AWS::ECS::TaskDefinition.ContainerDefinition, not a top-level property of AWS::ECS::TaskDefinition