/**
* Creates a new STUN <tt>Message</tt> to be sent to the STUN server associated with the
* <tt>StunCandidateHarvester</tt> of this instance in order to keep a specific
* <tt>LocalCandidate</tt> (harvested by this instance) alive.
*
* @param candidate the <tt>LocalCandidate</tt> (harvested by this instance) to create a new
* keep-alive STUN message for
* @return a new keep-alive STUN <tt>Message</tt> for the specified <tt>candidate</tt> or
* <tt>null</tt> if no keep-alive sending is to occur
* @throws StunException if anything goes wrong while creating the new keep-alive STUN
* <tt>Message</tt> for the specified <tt>candidate</tt> or the candidate is of an unsupported
* <tt>CandidateType</tt>
*/
protected Message createKeepAliveMessage(LocalCandidate candidate) throws StunException {
/*
* We'll not be keeping a STUN Binding alive for now. If we decide to in
* the future, we'll have to create a Binding Indication and add support
* for sending it.
*/
if (CandidateType.SERVER_REFLEXIVE_CANDIDATE.equals(candidate.getType())) return null;
else {
throw new StunException(StunException.ILLEGAL_ARGUMENT, "candidate");
}
}
