S3Client.headObject does not throw NoSuchKeyException as documented

[ghadishayban]

Expected Behavior

The docs say that headObject should return a NoSuchKeyException when not found.

Current Behavior

It does not throw NSKE. Instead, it throws an ordinary:

S3Exception null (Service: S3Client; Status Code: 404; Request ID: null)  software.amazon.awssdk.core.http.pipeline.stages.HandleResponseStage.handleErrorRes\
ponse (HandleResponseStage.java:114)

#147 appeared to fix this for getObject, but headObject still busted (there's even a test for it in that changeset.)

Steps to Reproduce (for bugs)

HEAD a non existent key with the S3Client

Your Environment

JDK 10 + AWS SDK v2 preview 10

[ghadishayban]

I will add, I really don't care for throwing exceptions in such a common case. HEAD will either return stat meta or not.

[codylerum]

Also see #297

[zoewangg]

This has been fixed as part of #830 and will be included in the next release.