Decorates a map iterator such that it cannot be modified.
since: Commons Collections 3.0 version: $Revision: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $ author: Stephen Colebourne
Decorates the specified iterator such that it cannot be modified.
Parameters: iterator - the iterator to decorate throws: IllegalArgumentException - if the iterator is null