Usage of N5Exception.N5IOException

[tpietzsch]

Several KeyValueAccess methods throw IOException.
Recently, N5Exception.N5IOException was introduced, and is now used in some places, but inconsistently.
For example some unit tests now expect N5IOException to be thrown. However many methods throw IOException instead.

For example, throwing N5IOException here

n5-aws-s3/src/main/java/org/janelia/saalfeldlab/n5/s3/AmazonS3KeyValueAccess.java

Line 77 in e326ec4

public AmazonS3KeyValueAccess(final AmazonS3 s3, final String bucketName, final boolean createBucket) throws N5Exception.N5IOException {

to make unit tests happy feels wrong, when all other methods there throw normal IOException as per KeyValueAccess interface declaration.

What is the idea with N5Exception.N5IOException? Why does it exist? Is it intended to replace all usage of IOException? Or when should the one or the other be chosen?