Where is the source code for all the examples in the <JINI_ROOT>/example directory of the Jini distribution?

All the Jini examples are part of the com.sun.jini.example package. Although you might expect the source to be in the example directory, as is the common practice for other Java API distributions, with Jini it's actually in the source tree mixed in with all of the core Jini API classes, i.e. in <JINI_ROOT>/source/vob/jive/src/com/sun/jini/example. (Here, <JINI_ROOT> refers to the base directory where Jini is installed, and paths are shown using Unix conventions.)