remove useless RouteResult.routeUnits

sharding-core/sharding-core-route/src/main/java/org/apache/shardingsphere/core/route/RouteResult.java

@@ -22,10 +22,6 @@ import lombok.RequiredArgsConstructor;
 import lombok.Setter;
 import org.apache.shardingsphere.core.route.type.RoutingResult;
 import org.apache.shardingsphere.sql.parser.relation.statement.SQLStatementContext;
-import org.apache.shardingsphere.underlying.route.RouteUnit;
-
-import java.util.Collection;
-import java.util.LinkedHashSet;
 
 /**
  * SQL route result.
@@ -41,7 +37,5 @@ public class RouteResult {
     
     private final SQLStatementContext sqlStatementContext;
     
-    private final Collection<RouteUnit> routeUnits = new LinkedHashSet<>();
-    
     private RoutingResult routingResult;
 }