@xerial Can you take a look at this pull request?

This pull request handles #426. The example code on the issue 426 actually includes the wrong usages (e.g. read/write a byte array without MessagePack header). But the issue itself can be reproduced with a test code this pull request includes.

BTW, the CI test for JDK9 on Travis CI isn't working https://travis-ci.org/msgpack/msgpack-java/jobs/246543240#L662. I have no idea about the error.