Native threads attached to 1.2 vm do not have names by default

Using JNI in jdk1.2, if a native thread does not set a thread name using
the interface, after it attaches to a VM, and calls
System.getCurrentThread().getName()
the result is an empty string (not returning null).

This is not correct, since threads should have a default name/identifier
even if users do not specify them before attaching to the vm. Also,
even if this is the new behavior in 1.2, it should return null rather
then an empty string when trying to get the thread name.