Hi Einar
About OjenJDK vs Java, I think that it is the same source code, with the difference that Oracle offers different licensing deals for Java and includes some close source components, and OpenJDK is GNU GPL. For what I know Java is the one officially supported by Oracle, and OpenJDK is the one for the open source community. So, for OS/2 our only option is to port/use OpenJDK, since making a licensing agreement to name it Java will cost money.
Here it the official wording:
Q: What is the difference between the source code found in the OpenJDK repository, and the code you use to build the Oracle JDK?
A: It is very close - our build process for Oracle JDK releases builds on OpenJDK 7 by adding just a couple of pieces, like the deployment code, which includes Oracle's implementation of the Java Plugin and Java WebStart, as well as some closed source third party components like a graphics rasterizer, some open source third party components, like Rhino, and a few bits and pieces here and there, like additional documentation or third party fonts. Moving forward, our intent is to open source all pieces of the Oracle JDK except those that we consider commercial features such as JRockit Mission Control (not yet available in Oracle JDK), and replace encumbered third party components with open source alternatives to achieve closer parity between the code bases.
Source: Oracle
About OpenJDK 8, that is up to the main developer "bww bitwise works", but it is also up to all us (community) to help them funding the development. It can be interesting to see if "bww bitwise works" has the time/people to update OpenJDK to version 8 and set up a funding goal for that one.
Regards