TradeUtils is used as a library for the address type

In OstiumTrading, the library TradeUtils is used for the address type:

contract OstiumTrading is IOstiumTrading, Delegatable, Initializable {
    using TradeUtils for address;

This is done in order to be able to directly use the return value of a call to registry.getContractAddress to call convenience functions in the library. However, attaching the library to address is overly broad and allows invalid calls like this to compile:

msg.sender.setTradeLastUpdated( /* [...] */ );

Moreover, it is unclear at a glance what is actually being called because the function in OstiumTradingCallbacks is also called setTradeLastUpdated but has a different signature, and the layer of calls in the library is hidden.

This issue has been acknowledged by Ostium Labs, and a fix was implemented in commit 9b977c93↗.