Fixed typo

src/main/java/envoy/data/IdGenerator.java

@@ -32,7 +32,7 @@ public class IdGenerator implements Serializable {
 	}
 
 	@Override
-	public String toString() { return String.format("MessageIdGenerator[current=%d,end=%d]", current, end); }
+	public String toString() { return String.format("IdGenerator[current=%d,end=%d]", current, end); }
 
 	/**
 	 * @return {@code true} if there are unused IDs remaining