Any word on getting this PR deconflicted and merged? It would be nice to have!

YamlWriter.close() is not simply releasing resources, the important thing is to convert the input object into yaml format and write it to the stream.

YamlReader.close() is to close the stream and release resources, this can implement Closeable interface.
@NathanSweet
YamlWriter and YamlReader needs to implement the Closeable interface.