AWSTemplateFormatVersion: '2010-09-09'

Description: Reproduce "semantic difference after formatting" error

Parameters:
  EnvironmentParam:
    Default: dev
    Type: String
    AllowedValues:
      - dev
      - prod

Mappings:
  EnvironmentMap:
    MappedParam:
      dev: my-dev-topic
      prod: my-prod-topic

Resources:
  Topic:
    Type: AWS::SNS::Topic
    Properties: 
      TopicName: !FindInMap [ EnvironmentMap, MappedParam, !Ref EnvironmentParam ]