jmap no -heap option

I would like to use jmap to create a heap summary (using jmap -heap). This is a standard utility that comes with the jdk and this is a standard feature. However, when I use the alpine:3.9 image and add the jdk (using apk add openjdk8), the version of jmap doesn't support the -heap option.

I originally posted this question here https://github.com/docker-library/openjdk/issues/286 but I think this is the correct place to raise the issue.

Any idea why the -heap option is not supported on alpine openjdk?

Thanks,

Allen