2) While the proposed feature may have some usage, I think that I
would want more control in what range the opened port number will be.
Just setting a "0" would not provide such control.
3) There are several Connector/Endpoint implementations in Tomcat.
While java.net.ServerSocket does support port number of "0", I am not
sure that APR-based implementation does allow it.
Sure but the use case is just to start a http/https (apr can be
omitted) connector on any random free port, do some unit test and stop
IMHO it's a valid use case (and with it folks will be able to use
tomcat rather than an other servlet container which has this feature
available :-) ).
See the code snippet I have pointed, the code to write for using
tomcat is really smaller/smarter (except all hacking I have to write
due to the restriction on port).