Custom user agent metadata does not appear in User-Agent header

[ianbotsf]

Describe the bug

When setting custom user age metadata via an aws.customMetadata.* system property, the expected values do not show up in requests's User-Agent header. Different metadata set via the aws.frameworkMetadata property do properly show up so this seems to be unique to custom metadata.

Expected behavior

Custom metadata set via aws.customMetadata.* are included in the User-Agent header.

Current behavior

Custom metadata set via aws.customMetadata.* are not included in the User-Agent header.

Steps to Reproduce

Configure DEBUG-level logging and run the following code:

System.setProperty("aws.customMetadata.foo", "bar")
val s3 = S3Client.fromEnvironment { sdkLogMode = SdkLogMode.LogRequest }
s3.listObjectsV2 { bucket = "<some-bucket>" }

View the DEBUG output and inspect the request headers. The User-Agent string contains other metadata but not the custom metadata foo=bar.

Possible Solution

No response

Context

No response

AWS Kotlin SDK version used

0.17.6-SNAPSHOT

Platform (JVM/JS/Native)

OpenJDK Runtime Environment Corretto-17.0.4.8.1 (build 17.0.4+8-LTS)

Operating System and version

Amazon Linux 2