docs: func (s *DescribeStackInstanceInput) Validate() error {
  	invalidParams := request.ErrInvalidParams{Context: "DescribeStackInstanceInput"}
  	if s.StackInstanceAccount == nil {
  		invalidParams.Add(request.NewErrParamRequired("StackInstanceAccount"))
  	}
  	if s.StackInstanceRegion == nil {
  		invalidParams.Add(request.NewErrParamRequired("StackInstanceRegion"))
  	}
  	if s.StackSetName == nil {
  		invalidParams.Add(request.NewErrParamRequired("StackSetName"))
  	}
  
  	if invalidParams.Len() > 0 {
  		return invalidParams
  	}
  	return nil
  }