ssm: Is the Value field on Parameter required?

[endgame]

I am a bit unsure about the Value field on the Parameter type of AWS Systems Manager (formerly known as SSM).

It is required according to docs on
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ssm-parameter.html

These docs don't mention anything about optionality, but they do mention the field and supply it in their examples:

• Systems Manager API reference for get_parameter method
  https://docs.aws.amazon.com/systems-manager/latest/APIReference/API_GetParameter.html
• Ruby Parameter docs
  https://docs.aws.amazon.com/sdk-for-ruby/v3/api/Aws/SSM/Types/Parameter.html
• Python get_parameter docs
  https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/ssm.html#SSM.Client.get_parameter

In the Go bindings, it is a pointer, which suggests that it is optional. But it seems like everything is a pointer.
https://docs.aws.amazon.com/sdk-for-go/api/service/ssm/#Parameter

This piece of Parameter documentation claims it is not required:
https://docs.aws.amazon.com/systems-manager/latest/APIReference/API_Parameter.html

So what to do? Don't know whether I should make a PR.

Originally posted by @ysangkok in #739 (comment)

[endgame]

I'm not certain that CloudFormation requiring a parameter is strong evidence that it's actually required. CloudFormation seems to be its own strange beast.

I'm pretty sure that all the docs you linked are downstream of the botocore definition, so if it says Value is not required then you'll get the behaviour you see.

I checked a GetParameter call with decryption disabled, and it returns encrypted data, so that's fine.
I tried to create a parameter with an empty value, but AWS APIs will refuse that - aws ssm put-parameter --name foo --value '' failed with a validation error.

So I think I'm satisfied that this is going to exist, and will merge a PR making this change. Please don't regenerate the service when you change it, we'll do a big regen in the new year.