code: @Override
      public List<String> getNodeTypes(CommandContext ctx, OperationRequestAddress prefix) {
          return Util.getNodeTypes(ctx.getModelControllerClient(), prefix);
      }
docs: /* (non-Javadoc)
  @see org.jboss.as.cli.CandidatesProvider#getNodeTypes(org.jboss.as.cli.Prefix)