public Builder setVolumes(Set<AbsoluteUnixPath> volumes) {
      this.volumes = new HashSet<>(volumes);
      return this;
    }
Sets the directories that may hold externally mounted volumes. Note that these values are
added to the base image values.

<p>This is similar to <a
href="https://docs.docker.com/engine/reference/builder/#volume">{@code VOLUME} in
Dockerfiles</a>.

@param volumes the directory paths on the container filesystem to set as volumes
@return this
jib-build-plan/src/main/java/com/google/cloud/tools/jib/api/buildplan/ContainerBuildPlan.java