To reproduce:
./build.sh -v -Dtest=org.jgroups.tests.FlushTest one-test

Output includes:
runtests:
Property ${testname.ext} has not been set
Property ${formatter.class} has not been set
[echo] Tests running with parameters:
[echo] channel.conf=udp.xml
[echo] channel.conf.flush=flush-udp.xml
[echo] mux.on=false
[echo] mux.conf=stacks.xml
[echo] mux.conf.stack=udp
[echo] mux.factorycount=4
[echo] threadcount=false
[echo] test.verbose=true
[echo] testname.ext=${testname.ext}
[echo] formatter.class=${formatter.class}
[echo]
[echo] Using set: one.test
Property ${testname.ext} has not been set
Property ${testname.ext} has not been set
[antcall] Exiting C:\JGroups\build.xml.

BUILD SUCCESSFUL
Total time: 1 second