code: public static Reference createAmbiguousReference
                      (String shortDefaultBinding,
                       List<J2EEName> j2eeNames)
      {
          String message = "The short-form default binding '" + shortDefaultBinding +
                           "' is ambiguous because multiple beans implement the interface : " +
                           j2eeNames + ". Provide an interface specific binding or use " +
                           "the long-form default binding on lookup.";
  
          StringRefAddr refAddr = new StringRefAddr(ADDR_TYPE, message);
          Reference ref = new Reference(ADDR_TYPE, refAddr,
                          AMBIGUOUS_FACTORY_NAME, null);
          return ref;
      }
docs: Creates an AmbiguousEJBReference Reference based on a short-form
  default binding (interface) and a list of J2EENames for all EJB
  implementing that interface, and using short-form bindings. <p>
  
  Intended for use in the following scenario: <p>
  
  Default short form bindings are being used, and multiple EJBs
  are configured to implement the same interface. <p>
  
  Since the short form binding does not uniquely identify a
  specific EJB, it is considered ambiguous. Instead, the
  lookup should be performed using the long form binding name,
  or a specific binding should be provided.
  
  @param shortDefaultBinding short-form default binding for an EJB.
  @param j2eeNames list of all EJBs implementing the same interface.
  
  @return the created AmbiguousEJBReference Reference.