Recipe for Java, JRE or JDK

Hi,

I wanted to use JOSM:
https://josm.openstreetmap.de/

so I will would need to have Java installed.

Looked for IcedTea to have an open source software:
http://icedtea.classpath.org/wiki/Main_Page

but as stated in the long list of requirements (IcedTea BuildRequirements):
http://icedtea.classpath.org/wiki/BuildRequirements
- A working Free Software JDK
- Ant >= 1.6.5 (Apache-Ant), that also requires a working JDK or SUN-JRE.

Also looked at OpenJDK:
http://openjdk.java.net/
- but also requires Ant, so same result here.

This is nonsense!
So to install an open source Java software, I need to have a previous
JRE or JDK installed?!

In our GoboLinux015 there is no Java, so even to be able to compile
IcedTea or OpenJDK, the easy way would be to get SUN-JRE, but the
existing recipes are old and outdated, links don't work anymore.

Nowadays, it's Oracle-JRE, so I tried to make a new recipe, but the
source is hard to get for the recipe (Autodownload bundle), and it no
longer comes in *.bin format.
I found a working source that may be used for the recipe, so the first
part is OK, but I need some help to complete the recipe, as my
knowledge is somewhat limited :)

What is necessary:
Recipe type= (?)   should it be 'manifest', like SUN-JRE?
This Oracle-JRE is ready to use, just needs to be unpacked and placed
in its place (don't know how compile does this).

It's also necessary to add a folder in Firefox, in
/Programs/Firefox/Current/firefox/browser/plugins, and in that
'plugins' folder, create a link for the new Java plugin, that will be
in /Programs/Oracle-JRE/Current/lib/i386/libnpjp2.so

So, something like this?

compile_version=2.0
url="http://ftp.osuosl.org/pub/funtoo/distfiles/oracle-java/jre-7u65-linux-i586.tar.gz"
file_size=48423426
file_md5=d11d9f4488d75106fc8909b847efaeda
dir='jre1.7.0_65'

recipe_type= (?)

pre_link() {
  # Create a link to the java plugin in the standard browser-plugins directory
  # Is this correct?
  mkdir -p ${target}/Firefox/Current/firefox/browser/plugins
  ln -s ${target}/Oracle-JRE/Current/lib/i386/libnpjp2.so
${target}/Firefox/Current/firefox/browser/plugins
}