A unique identifier that you specify. This identifier is not the same as the pipeline identifier assigned by AWS Data Pipeline. You are
            responsible for defining the format and ensuring the uniqueness of this identifier. You use this parameter to ensure idempotency during
            repeated calls to CreatePipeline. For example, if the first call to CreatePipeline does not return a clear success, you can
            pass in the same unique identifier and pipeline name combination on a subsequent call to CreatePipeline. CreatePipeline
            ensures that if a pipeline already exists with the same name and unique identifier, a new pipeline will not be created. Instead, you'll
            receive the pipeline identifier from the previous attempt. The uniqueness of the name and unique identifier combination is scoped to the AWS
            account or IAM user credentials.
             
            
Constraints:
 Declaration Syntax
 Declaration Syntax| C# | 
public string UniqueId { get; set; }