RegistrationTreeNode<T> ensureChild(@Nonnull final PathArgument child) {
RegistrationTreeNode<T> potential = children.get(Preconditions.checkNotNull(child));
if (potential == null) {
RegistrationTreeNode<T> ensureChild(@Nonnull final PathArgument child) {
RegistrationTreeNode<T> potential = children.get(Preconditions.checkNotNull(child));
if (potential == null) {