[Fleet] Fix frozen key definition (#99232)

* [Fleet] Fix frozen key definition

* Add integration test for frozen vars

x-pack/plugins/fleet/server/types/models/package_policy.ts

@@ -24,6 +24,7 @@ const ConfigRecordSchema = schema.recordOf(
   schema.object({
     type: schema.maybe(schema.string()),
     value: schema.maybe(schema.any()),
+    frozen: schema.maybe(schema.boolean()),
   })
 );
 

x-pack/test/fleet_api_integration/apis/package_policy/update.ts

@@ -174,5 +174,42 @@ export default function (providerContext: FtrProviderContext) {
         })
         .expect(500);
     });
+
+    it('should work with frozen input vars', async function () {
+      await supertest
+        .put(`/api/fleet/package_policies/${packagePolicyId}`)
+        .set('kbn-xsrf', 'xxxx')
+        .send({
+          name: 'filetest-1',
+          description: '',
+          namespace: 'updated_namespace',
+          policy_id: agentPolicyId,
+          enabled: true,
+          output_id: '',
+          inputs: [
+            {
+              enabled: true,
+              type: 'test-input',
+              streams: [],
+              vars: {
+                frozen_var: {
+                  type: 'text',
+                  value: 'abc',
+                  frozen: true,
+                },
+                unfrozen_var: {
+                  type: 'text',
+                  value: 'def',
+                },
+              },
+            },
+          ],
+          package: {
+            name: 'filetest',
+            title: 'For File Tests',
+            version: '0.1.0',
+          },
+        });
+    });
   });
 }