DEX-994 fixed toString

Author: Evgeniya Tsybrenko

dex-common/src/main/scala/com/wavesplatform/dex/api/http/entities/HttpLastTrade.scala

@@ -2,4 +2,6 @@ package com.wavesplatform.dex.api.http.entities
 
 import com.wavesplatform.dex.domain.order.OrderType
 
-final case class HttpLastTrade(price: Long, amount: Long, side: OrderType)
+final case class HttpLastTrade(price: Long, amount: Long, side: OrderType) {
+  override def toString: String = s"LastTrade(p=$price, a=$amount, $side)"
+}