Howl benchmark was removed by the following changeset, but library jar is still in the repository:
micros-jdk6/src/main/resources/org/objectweb/howl/howl/1.0.2/howl-1.0.2.jar

$ hg log -r 313 -v
changeset: 313:f06aeb82b3be
user: shade
date: Tue Aug 13 12:10:30 2013 +0400
files: micros-jdk6/pom.xml micros-jdk6/src/main/java/oracle/micro/benchmarks/app/howl/Howl.java
description:
Phase out legacy Howl benchmark.