Throw more granular exception on ImageAnnotatorClient.close()

[gguuss]

Currently, the image annotator client can throw the generic "Exception" on close. I found this while making the update to close the image annotator client in the vision sample.

[michaelbausor]

I think this may be unavoidable, because the AutoCloseable interface throws Exception: https://docs.oracle.com/javase/7/docs/api/java/lang/AutoCloseable.html#close()

[michaelbausor]

Relevant code in image annotator client: https://github.com/GoogleCloudPlatform/google-cloud-java/blob/master/google-cloud-vision/src/main/java/com/google/cloud/vision/v1/ImageAnnotatorClient.java#L232

[gguuss]

I see, it sounds like they "strongly encourage implementations to throw more specific exceptions" but it's not clear how they expect you to implement this.

[michaelbausor]

Yes, it isn't clear what we could do. One possibility would be to use a list of Closeable instead of Autocloseable. But I would be worried that at some future point, we would want to add an Autocloseable and need to change it back.

I am closing this for now, but if you want to discuss possibly switching to Closeable or some other option, please reopen!