if ( ( reference == null ) || ( referee == null ) )
{
return;
}
SchemaObjectWrapper wrapper = new SchemaObjectWrapper( referee );
Set<SchemaObjectWrapper> uses = getUsedBy( referee );
if ( uses == null )
{
uses = new HashSet<SchemaObjectWrapper>();
}
uses.add( new SchemaObjectWrapper( reference ) );
// Put back the set (this is a concurrentHashMap, it won't be replaced implicitly
usedBy.put( wrapper, uses );
}