Protocol test InputAndOutputWithTimestampHeaders contains quotes for RestJSON but not for RestXml

[trivikr]

Links to the code

RestJSON https://github.com/awslabs/smithy/blob/78a3ac958ea442695cf66ad0f5808768e1f553bf/smithy-aws-protocol-tests/model/restJson1/http-headers.smithy#L108-L121

RestXML: https://github.com/awslabs/smithy/blob/75928a7c69b2a156382b5d8bc87a6991f5fea64e/smithy-aws-protocol-tests/model/restXml/http-headers.smithy#L93-L106

Observation

This appears to be a bug, as the behavior for the list of timestamps should be same across protocols

Additional Context

• This issue was noticed while bumping AWS SDK for JavaScript (v3) to smithy 1.15.x chore(codegen): bump smithy to 1.15.x aws/aws-sdk-js-v3#3091 (comment)
• The protocol tests for quotes string were added in Add tests for quoted strings in headers #986

[gosar]

In #1023 reverted escaping of timestamp header in restJson1. Now restJson1 and restXml are same.