Description of problem:
Heat 9.0.0 (Pike) is supposed to support OS::Neutron::Segment resources. This is a requirement for routed spine-and-leaf (under development). Heat is giving this error:
ERROR: The Resource Type (OS::Neutron::Segment) could not be found.

Version-Release number of selected component (if applicable):
openstack-heat-api.noarch                                                                1:9.0.0-0.20170420143908.a9c423c.el7.centos                                                             @delorean
openstack-heat-api-cfn.noarch                                                            1:9.0.0-0.20170420143908.a9c423c.el7.centos                                                             @delorean
openstack-heat-common.noarch                                                             1:9.0.0-0.20170420143908.a9c423c.el7.centos                                                             @delorean
openstack-heat-engine.noarch                                                             1:9.0.0-0.20170420143908.a9c423c.el7.centos                                                             @delorean
20


How reproducible:
100%

Steps to Reproduce:

Here is an example template that will trigger the bug:

###########
heat_template_version: 2017-09-01

description: Template to create an ironic instance

parameters:

  TestNetValueSpecs:
    default: {'provider:physical_network': 'ctlplane', 'provider:network_type': 'flat'}
    description: Value specs for the internal API network.
    type: json

resources:

  test_network:
    type: OS::Neutron::Net
    properties:
      admin_state_up: True
      name: test-network
      shared: True
      value_specs: {get_param: TestNetValueSpecs}

  test_segment:
    type: OS::Neutron::Segment
    properties:
      network: test-network
      network_type: flat
      name: test-segment1
      physical_network: test_network
###########

Actual results:
$ openstack stack create -t template.yaml test_stack
ERROR: The Resource Type (OS::Neutron::Segment) could not be found.


Expected results:
A Neutron Segment should be created.

Additional info:
Prior to this testing, I enabled segments in the service_plugins in neutron.conf.

The feature in Heat is shown here, and it is listed as being supported in 9.0.0:
https://docs.openstack.org/developer/heat/template_guide/openstack.html#OS::Neutron::Segment