Baseclass for the <condition> task as well as several
conditions - ensures that the types of conditions inside the task
and the "container" conditions are in sync.
Test for a host being reachable using ICMP "ping" packets & echo operations.
Ping packets are very reliable for assessing reachability in a LAN or WAN,
but they do not get through any well-configured firewall.
Checks whether a jarfile is signed: if the name of the
signature is passed, the file is checked for presence of that
particular signature; otherwise the file is checked for the
existence of any signature.