private static ImmutableList<QName> checkQNames(final Collection<QName> qnames) {
final ImmutableList<QName> ret = ImmutableList.copyOf(qnames);
checkArgument(!ret.isEmpty(), "SchemaNodeIdentifier has to have at least one node identifier");
private static ImmutableList<QName> checkQNames(final Collection<QName> qnames) {
final ImmutableList<QName> ret = ImmutableList.copyOf(qnames);
checkArgument(!ret.isEmpty(), "SchemaNodeIdentifier has to have at least one node identifier");