Add feature flag for backup agent type of binding

[finishes #171725367]

jobs/broker/spec

@@ -298,7 +298,7 @@ properties:
   service_catalog.maintenance_info.description:
     description: maintenance information description of the impact of the maintenance update for all plans. See https://github.com/openservicebrokerapi/servicebroker/blob/master/spec.md#maintenance-info-object
     default:
-  
+
   service_catalog.maintenance_info.public:
     description: maintenance information to be returned as plain text in the service catalog for all plans
     default: {}
@@ -312,3 +312,7 @@ properties:
 
   startup_banner:
     default: false
+
+  support_backup_agent_binding:
+    description: If the service adapter supports backup agent URL bindings, set this flag to true
+    default: false

jobs/broker/templates/broker.yml.erb

@@ -439,6 +439,7 @@ config = {
     "use_stdin" => p('use_stdin'),
     "enable_secure_manifests" => p('enable_secure_manifests'),
     "enable_telemetry" => p('enable_telemetry'),
+    "support_backup_agent_binding" => p('support_backup_agent_binding'),
   }.merge(tls_config),
   "bosh" => bosh_config,
   "cf" => cf_config,

spec/broker_config_template_spec.rb

@@ -1539,6 +1539,46 @@
       end
     end
   end
+
+  describe 'backup agent URL binding support' do
+    context 'when not set' do
+      let(:manifest_file) do
+        generate_test_manifest do |yaml|
+          yaml['instance_groups'][0]['jobs'][0]['properties'].delete('support_backup_agent_binding')
+        end
+      end
+
+      it 'defaults to false' do
+        expect(rendered_template).to include 'support_backup_agent_binding: false'
+      end
+    end
+
+    context 'when disabled' do
+      let(:manifest_file) do
+        generate_test_manifest do |yaml|
+          yaml['instance_groups'][0]['jobs'][0]['properties']['support_backup_agent_binding'] = false
+        end
+      end
+
+      it 'is set to false' do
+        config = YAML.safe_load(rendered_template)
+        expect(config.dig('broker', 'support_backup_agent_binding')).to eq(false)
+      end
+    end
+
+    context 'when enabled' do
+      let(:manifest_file) do
+        generate_test_manifest do |yaml|
+          yaml['instance_groups'][0]['jobs'][0]['properties']['support_backup_agent_binding'] = true
+        end
+      end
+
+      it 'is set to trie' do
+        config = YAML.safe_load(rendered_template)
+        expect(config.dig('broker', 'support_backup_agent_binding')).to eq(true)
+      end
+    end
+  end
 end
 
 def generate_test_manifest