Use presence for every attribute

Use presence for every attribute in
`Gitlab::Alerting::NotificationPayloadParser`

ee/lib/gitlab/alerting/notification_payload_parser.rb

@@ -31,15 +31,15 @@ module Gitlab
       def annotations
         {
           'title' => title,
-          'description' => payload[:description],
-          'monitoring_tool' => payload[:monitoring_tool],
-          'service' => payload[:service],
+          'description' => payload[:description].presence,
+          'monitoring_tool' => payload[:monitoring_tool].presence,
+          'service' => payload[:service].presence,
           'hosts' => hosts
         }.compact
       end
 
       def hosts
-        payload[:hosts].presence && Array(payload[:hosts])
+        Array(payload[:hosts]).reject(&:blank?).presence
       end
 
       def current_time

ee/spec/lib/gitlab/alerting/notification_payload_parser_spec.rb

@@ -58,7 +58,7 @@ describe Gitlab::Alerting::NotificationPayloadParser do
         payload[:start_time] = 'invalid/date/format'
       end
 
-      it 'sets startsAt to a currurrent time in RFC3339 format' do
+      it 'sets startsAt to a current time in RFC3339 format' do
         expect(subject['startsAt']).to eq(starts_at.rfc3339)
       end
     end
@@ -73,5 +73,25 @@ describe Gitlab::Alerting::NotificationPayloadParser do
         )
       end
     end
+
+    context 'when payload attributes have blank lines' do
+      let(:payload) do
+        {
+          'title' => '',
+          'start_time' => '',
+          'description' => '',
+          'monitoring_tool' => '',
+          'service' => '',
+          'hosts' => ['']
+        }
+      end
+
+      it 'returns default parameters' do
+        is_expected.to eq(
+          'annotations' => { 'title' => 'New: Incident' },
+          'startsAt' => starts_at.rfc3339
+        )
+      end
+    end
   end
 end