Create Vulnerability serializer

ee/app/serializers/vulnerability_entity.rb

+# frozen_string_literal: true
+
+class VulnerabilityEntity < Grape::Entity
+  include RequestAwareEntity
+
+  expose :id,
+    :title,
+    :state,
+    :severity,
+    :confidence,
+    :report_type,
+    :resolved_on_default_branch,
+    :project_default_branch,
+    :resolved_by_id,
+    :dismissed_by_id,
+    :confirmed_by_id
+end

ee/app/serializers/vulnerability_serializer.rb

+# frozen_string_literal: true
+
+class VulnerabilitySerializer < BaseSerializer
+  entity VulnerabilityEntity
+end

ee/spec/serializers/vulnerability_entity_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe VulnerabilityEntity do
+  let(:entity) { described_class.new(vulnerability) }
+  let(:vulnerability) { create(:vulnerability, project: project, author: user) }
+  let(:project) { create(:project) }
+  let(:user) { create(:user) }
+
+  subject { entity.as_json }
+
+  it 'exposes vulnerability-specific elements' do
+    expect(subject).to match(
+      id: vulnerability.id,
+      title: vulnerability.title,
+      state: vulnerability.state,
+      severity: vulnerability.severity,
+      confidence: vulnerability.confidence,
+      report_type: vulnerability.report_type,
+      resolved_on_default_branch: vulnerability.resolved_on_default_branch,
+      project_default_branch: vulnerability.project_default_branch
+    )
+  end
+end