This tasks requires updating a .bep file to allow Haikuporter to build from source code the listed package.  You will need a working installation of Haiku, this could be on real hardware or in a VM, and haikuporter which can be installed by following the install instructions at HaikuPorts

Some knowledge of C, C++ may or may not be required in order to complete this task.  Knowledge of the GNU autotools and/or cmake may also be helpful.  The package may or may not require some patching to get it to work on Haiku.  For these cases don't be afraid to ask for help.  Many compile issues can be figured out by reading through the various wiki pages at HaikuPorts.  Also google (or other web search engine) may be of help in finding solutions to build issues that you may run into, irc channel #haiku on freenode might also be of help.  Be sure to follow the correct format for creating your .bep file, including the license and copyright entries.

You'll find the current openjdk .bep file in dev-lang/openjdk once you install Haikuporter.  There's an article on the Haiku website explaining how to build OpenJDK manually.  The current .bep file was a preliminary attempt to automate the process.