E2001: type of a { Fn::ImportValue } is not considered a string when used as a Parameter default

[rix0rrr]

{
 "Parameters": {
  "SomeParameter": {
   "Type": "String",
   "Default": {
    "Fn::ImportValue": "Stack1:ExportsOutputRefAWSAccountIdAD568057"
   }
  }
 }
}

Leads to

    WARNING Parameters.SomeParameter.Default: Parameter 'SomeParameter': Default must be a string (CloudFormation Validate)
       
       Acknowledge with 'CloudFormation-Validate::E2001'

[satyakigh]

This is actually invalid syntax, can be reproduced with the sample template in the repo. Validated in #229

aws cloudformation validate-template --template-body file://src/resources/templates/gh-issues/issue-194.json

An error occurred (ValidationError) when calling the ValidateTemplate operation: Template format error: Every Default member must be a string.