question: public List < HashMap < String , Object > > clearOverallChat ( ) { try { List < HashMap < String , Object > > myChatList = myChats . get ( overallChatRoomName ) ; myChatList = new LinkedList < HashMap < String , Object > > ( ) ; myChats . put ( overallChatRoomName , myChatList ) ; Map < Integer , String > newMessage = new HashMap < Integer , String > ( ) ; newMessage . put ( 0 , "clearOverallChatHistory" ) ; scopeApplicationAdapter . sendMessageToMembers ( newMessage ) ; return myChatList ; } catch ( Exception err ) { log . error ( "[clearChat] " , err ) ; return null ; } }
target:  clear the overallChat history