A Chained Exception facility was added to the Throwable class in 1.4
(see RFE 4209652). This allows an exception to indicate that it was
thrown due to some other exception. By the time this facility was
added, a number of exception classes were using ad-hoc solutions to
the same problem. When 4209652 was integrated most of these ad-hoc
solutions were brought into line with the new generic facility but --
probably due to time constraints -- javax.naming.NamingException was not.

NamingException's behavior is already consistent with the treatment
given to other legacy classes, so only the javadoc needs to be updated
for consistency.