public IConcordionExtender WithCommand(string namespaceURI, string commandName, ICommand command)
{
Check.NotEmpty(namespaceURI, "Namespace URI is mandatory");
Check.NotEmpty(commandName, "Command name is mandatory");
Check.NotNull(command, "Command is null");
Check.IsFalse(namespaceURI.StartsWith("Concordion"),
"The namespace URI for user-contributed command '" + commandName + "' "
+ "must not start with 'Concordion'. Use your own domain name instead.");
return WithApprovedCommand(namespaceURI, commandName, command);
}