}
@Override
public NamespaceImplementor of(String namespaceName) {
checkNotNull(namespaceName, "namespaceName");
NamespaceImplementor namespace = namespaces.get(namespaceName);
if (namespace == null) {
NamespaceImplementor created = createNamespace(namespaceName);
namespace = namespaces.putIfAbsent(namespaceName, created);
if (namespace == null) {
namespace = created;
}
}