In @httpRequestTests, header values must be strings:

headers: StringMap

However, headers in Smithy can be represented by lists. It appears that the way to represent that in a compliance test is by comma-separating values in the string. However, this makes it impossible to disambiguate between:

• one value that actually contains a comma, and
• multiple values, separated by commas.

The spec seems to be lenient:

When a list shape is targeted, each member of the shape is serialized as a separate HTTP header either by concatenating the values with a comma on a single line or by serializing each header value on its own line.

but the compliance test traits only supports one style. Is that by design?