I just read the gettext-commons tutorial. However, I miss explanation of the way how the resource bundle entries are
created, i.e. how are key and value of a resource bundle entry constructed. If you know more about it, please explain it
here or send a link to such an explanation.

for the following piece of code

    localizedString = i18n.tr("Hello, World");

the corresponding entry in the Bundle_de.properties file would be:

Hello, World=Hallo, Welt

English (or another language that is choosed as standard)
translation is already in the code.

Thanks. I was not sure whether the English strings are really used as resource bundle keys.