code: @Override
      public Collection<? extends NameClassPair> listInstances(JavaColonNamespace namespace, String nameInContext) {
          final boolean isTraceOn = TraceComponent.isAnyTracingEnabled();
          if (isTraceOn && tc.isEntryEnabled())
              Tr.entry(tc, "listInstances (" + namespace + ", " + nameInContext + ")");
  
          // This helper only provides support for java:comp/env
          if ((namespace == JavaColonNamespace.COMP) && ("".equals(nameInContext))) {
              ArrayList<NameClassPair> retVal = new ArrayList<NameClassPair>();
              retVal.add(new NameClassPair(VALIDATOR_FACTORY, ValidatorFactory.class.getName()));
              retVal.add(new NameClassPair(VALIDATOR, Validator.class.getName()));
              if (isTraceOn && tc.isEntryEnabled())
                  Tr.exit(tc, "listInstances", retVal);
              return retVal;
          } else {
              if (isTraceOn && tc.isEntryEnabled())
                  Tr.exit(tc, "listInstances", "empty (not COMP)");
              return Collections.emptyList();
          }
  
      }
docs: {@inheritDoc}