Minor Description
ParserInitializationException appears to have its own rootCause instance variable, rather than using RuntimeException's constructors which allow a cause to be specified (ParserInitializationException extends RuntimeException). So for example on line 53 of this class [1], I would expect to see a simple invocation to super(message, rootCause).
The reason this has come up is that we're logging these exceptions using log4j, but because ParserInitializationException doesn't use the standard JDK exception chaining, we don't get visibility into the root issue in the logs.
This was discussed briefly on the user mailing list [2].
[1] http://svn.apache.org/viewvc/commons/proper/net/trunk/src/main/java/org/apache/commons/net/ftp/parser/ParserInitializationException.java?view=markup
[2] http://markmail.org/thread/6hn3doow352ic6ho