OpenJDK Project Valhalla investigation

[shakuzen]

There may be opportunities for Micrometer to take advantage of planned features of Project Valhalla. We should investigate what changes are needed in our codebase to take advantage of the features, and we should check any compatibility and performance changes. An early access build is available for testing. Value Class and Objects is the first planned feature of Project Valhalla and so that's where we should focus initial investigation.