Currently, when a user sets a chunk size, the channel rounds this down to the nearest multiple of MIN_CHUNK_SIZE (256K)

https://github.com/GoogleCloudPlatform/google-cloud-java/blob/master/google-cloud-core/src/main/java/com/google/cloud/BaseWriteChannel.java#L106

This does not seem to be consistent with its javadoc, which says it sets the minimum amount of data sent in an RPC
https://github.com/GoogleCloudPlatform/google-cloud-java/blob/master/google-cloud-core/src/main/java/com/google/cloud/WriteChannel.java#L34

With the rounding down, the RPC will actually have less than the minimum. I'm not sure why the rounding to chunk size multiple is needed, but if it can't be removed, it should round up instead of down.