Cloned from launchpad blueprint https://blueprints.launchpad.net/heat/+spec/nova-flavors.
Some template developers want to include flavors in their templates. see thread;
Specification URL (additional information):
This resource type was moved into the main tree in Liberty, so it should be available from RHOS 8 on.
According to our records, this should be resolved by openstack-heat-5.0.1-1.el7ost. This build is available now.