Do not assign lid when type does not match

Add test for cache

Alternaive solution to 7325

packages/-ember-data/tests/integration/identifiers/polymorphic-scenarios-test.ts

@@ -83,6 +83,9 @@ module('Integration | Identifiers - single-table-inheritance polymorphic scenari
 
       const foundFerrari = await store.findRecord('car', '1');
       assert.strictEqual(foundFerrari.constructor.modelName, 'ferrari', 'We found the right type');
+
+      const cachedFerrari = await store.peekRecord('ferrari', '1');
+      assert.strictEqual(cachedFerrari.constructor.modelName, 'ferrari', 'We cached the right type');
     });
 
     test(`Identity of polymorphic relations can change type when in cache`, async function(assert) {

packages/store/addon/-private/identifiers/cache.ts

@@ -343,6 +343,17 @@ export class IdentifierCache {
     let newId = coerceId(data.id);
     let existingIdentifier = detectMerge(this._cache.types, identifier, data, newId, this._cache.lids);
 
+    if (!existingIdentifier) {
+      // If the incoming type does not match the identifier type, we need to create an identifier for the incoming
+      // data so we can merge the incoming data with the existing identifier, see #7325 and #7363
+      if (identifier.type !== data.type && data.type) {
+        let incomingDataResource = Object.assign({}, data);
+        // Need to strip the lid from the incomingData in order force a new identifier creation
+        delete incomingDataResource.lid;
+        existingIdentifier = this.getOrCreateRecordIdentifier(incomingDataResource);
+      }
+    }
+
     if (existingIdentifier) {
       let keyOptions = getTypeIndex(this._cache.types, identifier.type);
       identifier = this._mergeRecordIdentifiers(keyOptions, identifier, existingIdentifier, data, newId as string);