java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to java.util.Collection

just a little note before the description. i am only the translator and did not experience this issue on my own, so it may takes some time for me to get the response from the server owners. sorry about that

This is a bug has been tested on Windows Server 2003, 2008, CentOS with Java 7 since build #666 ( have not tested before that)
All tests was running under offline mode. ( and of course not possible in online-mode

here is an example:
when a player joined the server with name...

java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to java.util.Collection