Assert.notNull(uri, "Namespace definition cannot supply a null URI");
final NamespaceHandler namespaceHandler = namespaceHandlerResolver.resolve(uri);
if (namespaceHandler == null) {
throw new BeanDefinitionParsingException(
new Problem("No namespace handler found for URI: " + uri,
new Location(readerContext.getResource())));
}
namespaceHandlers.put(namespace, namespaceHandler);
namespaces.put(namespace, uri);
}