dissappearing exception types from method signature

[Stuart Barlow]

I have a java interface with the following method...

public String logon(String libraryName, String userName, String domain, String 
password) throws DmSystemException, DmInvalidLogonException;

After I run Java2WSDL and WSDL2Java the method has changed to...

public java.lang.String logon(java.lang.String libraryName, java.lang.String 
userName, java.lang.String domain, java.lang.String password) throws 
java.rmi.RemoteException, com.hummingbird.hc.dm.api.DmSystemException;

DmInvalidLogonException derives from DmSystemException which derives
from java.lang.Exception
Why has the DmInvalidLogonException dissappeared from the signature?

Thanks,
Stuart.