Override toString method of class UserGroup to output object as JSON.

src/main/java/cm/soungui/guacamole/ext/wallix/sync/db/UserGroup.java

@@ -29,5 +29,19 @@ public class UserGroup extends Entity {
 	public Set<Entity> getMembers() {
 		return members;
 	}
+	
+	@Override
+	public String toString() {
+		StringBuffer output = new StringBuffer();
+		output.append("{id: ").append(getId())
+		.append(", group_id: ").append(getGroupId())
+		.append(", name: ").append(getName())
+		.append(", members: {");
+		for (Entity member : getMembers()) {
+			output.append(member.getType()).append(":").append(member.getName()).append(",");
+		}
+		output.deleteCharAt(output.length()-1).append("}");
+		return output.toString();
+	}
 
 }