Description of problem:

After changing service level using subscription manager it does not make any changes on Content Host profile on WebUI.

Version-Release number of selected component (if applicable):

6.2.10

How reproducible:

Everytime

Steps to Reproduce:
1. Register a system on Satellite using subscription-manager.
2. Set Premium as service level on content host profile.
3. Unset service level from client system,

# subscription-manager service-level --unset 
Service level preference has been unset

This makes no changes on WebUI.

Actual results:

Service level does not change on Content Host system profile.

Expected results:

Service level changes should be reflected on WebUI for Content Hosts page.

Additional info:

1. On Satellite if I manually update service_level using subscription_facet then I can see it changes on Content Hosts page.

# vim /opt/theforeman/tfm/root/usr/share/gems/gems/katello-3.0.0.137/app/controllers/katello/api/rhsm/candlepin_proxies_controller.rb

247     def facts
248       User.current = User.anonymous_admin
249       async_task(::Actions::Katello::Host::Update, @host, rhsm_params)
250       Rails.logger.info("amit debug: #{rhsm_params[:serviceLevel]}")
251       @host.subscription_facet[:service_level] = rhsm_params[:serviceLevel]
252       @host.subscription_facet.save!
253       #Katello::Host::SubscriptionFacet.update_facts(@host, rhsm_params)
254       render :json => {:content => _("Facts successfully updated.")}, :status => 200
255     end

2. On upstream Foreman instance if I try to unset service level then it fails as below,

2017-06-29 14:02:59 ba103d50 [app] [I] Processing by Katello::Api::Rhsm::CandlepinProxiesController#facts as JSON
2017-06-29 14:02:59 ba103d50 [app] [I]   Parameters: {"serviceLevel"=>"", "id"=>"32584679-f348-4349-a711-a7f8b472758f"}
2017-06-29 14:02:59 ba103d50 [foreman-tasks/dynflow] [W] Error on on_execution_plan_save event
 | ActiveRecord::RecordInvalid: Validation failed: Resource can't be blank

http://pastebin.test.redhat.com/498781