Current implementation of JMXServiceURL states that hyphens are only legal within a namespace component, not at the beginning or the end, so an address like a-b.c-d.e is legal but -ab.c-d.e or ab-.c-d.e isn't.
The DNS and/or URL specs evolved since so that these are now legal.
The java.net.URI class has been updated with the new spec but JMXServiceURL hasn't.