fix(datastore):predicate handling for observe (#1537)

Author: rjuliano

aws-datastore/src/main/java/com/amplifyframework/datastore/AWSDataStorePlugin.java

@@ -621,7 +621,7 @@ public <T extends Model> void observe(
             itemChange -> {
                 try {
                     if (itemChange.modelSchema().getName().equals(itemClass.getSimpleName()) &&
-                            selectionCriteria.evaluate(itemChange)) {
+                            selectionCriteria.evaluate(itemChange.item())) {
                         @SuppressWarnings("unchecked") // itemClass() was just inspected above. This is safe.
                         StorageItemChange<T> typedChange = (StorageItemChange<T>) itemChange;
                         onDataStoreItemChange.accept(ItemChangeMapper.map(typedChange));

aws-datastore/src/test/java/com/amplifyframework/datastore/AWSDataStorePluginTest.java

@@ -36,12 +36,10 @@
 import com.amplifyframework.core.InitializationStatus;
 import com.amplifyframework.core.category.CategoryType;
 import com.amplifyframework.core.model.ModelProvider;
-import com.amplifyframework.core.model.query.predicate.QueryField;
 import com.amplifyframework.core.model.temporal.Temporal;
 import com.amplifyframework.datastore.appsync.ModelMetadata;
 import com.amplifyframework.datastore.appsync.ModelWithMetadata;
 import com.amplifyframework.datastore.model.SimpleModelProvider;
-import com.amplifyframework.datastore.storage.StorageItemChange;
 import com.amplifyframework.hub.HubChannel;
 import com.amplifyframework.hub.HubEvent;
 import com.amplifyframework.logging.Logger;
@@ -579,7 +577,7 @@ public void accept(@NonNull DataStoreItemChange<Person> value) {
             }
         });
         awsDataStorePlugin.observe(Person.class,
-            QueryField.field("type").eq(StorageItemChange.Type.CREATE),
+            Person.FIRST_NAME.eq("Test"),
             value -> { },
             onObserveResult,
             error -> {
@@ -620,7 +618,7 @@ public void accept(@NonNull DataStoreItemChange<Person> value) {
             }
         });
         awsDataStorePlugin.observe(Person.class,
-            QueryField.field("type").eq(StorageItemChange.Type.UPDATE),
+            Person.FIRST_NAME.eq("NO MATCH"),
             value -> { },
             onObserveResult,
             error -> {