package Ġcom . sw iss chain . matching . engine . services . validators Ċ Ċ import Ġcom . sw iss chain . matching . engine . da os . Limit Order Ċ import Ġcom . sw iss chain . matching . engine . da os . Market Order Ċ import Ġcom . sw iss chain . matching . engine . da os . fee . v 2 . New Fee Instruction Ċ import Ġjava . util . concurrent . Priority BlockingQueue ĊĊ Ċ interface ĠMarket Order Validator Ġ{ ĊĠĠĠ Ġfun Ġperform Validation ( order : ĠMarket Order , Ġorder Book : ĠPriority BlockingQueue < Limit Order >, Ġfee Instructions : ĠList < New Fee Instruction > ?) Ċ }