PublicAPI: add test for setting icon via parameter.

Follow-up to #1818.

src/main/java/de/dennisguse/opentracks/data/models/Track.java

@@ -130,6 +130,16 @@ public class Track {
         this.trackStatistics = trackStatistics;
     }
 
+    @Override
+    public String toString() {
+        return "Track{" +
+                "name='" + name + '\'' +
+                ", description='" + description + '\'' +
+                ", activityTypeLocalized='" + activityTypeLocalized + '\'' +
+                ", activityType=" + activityType +
+                '}';
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;