There is no POAHelper class in package org.omg.CORBA.PortableServer. Jdk 1.4 Beta3-b83. Even the POA is pseudo IDL according to specification it must be handled like other CORBA object (narrowing using naarrow method). So the right way to get POA reference is:
POA poa = POAHelper.narrow (orb.resolve_initial_references ("RootPOA"))
if there is no POAHelper, the JDK1.4 is not able to run or compile the CORBA 2.3 servers.