docs: adds OR filter sample (#1032)

* docs: adds OR filter sample

Author: telpirion

README.md

@@ -268,6 +268,7 @@ Samples are in the [`samples/`](https://github.com/googleapis/java-datastore/tre
 | Count Aggregation With Order By | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithOrderBy.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithOrderBy.java) |
 | Count Aggregation With Property Filter | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithPropertyFilter.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithPropertyFilter.java) |
 | Count Aggregation With Stale Read | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithStaleRead.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/datastore/aggregation/CountAggregationWithStaleRead.java) |
+| Create a union between two filters | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/example/datastore/filters/OrFilterQuery.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/datastore/filters/OrFilterQuery.java) |
 | Task List | [source code](https://github.com/googleapis/java-datastore/blob/main/samples/snippets/src/main/java/com/google/datastore/snippets/TaskList.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-datastore&page=editor&open_in_editor=samples/snippets/src/main/java/com/google/datastore/snippets/TaskList.java) |
 
 

samples/snippets/src/main/java/com/example/datastore/filters/OrFilterQuery.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.datastore.filters;
+
+// sample-metadata:
+//   title: Create a union between two filters
+//   description: Create a union between two filters (logical OR operator)
+
+// [START datastore_query_filter_or]
+import com.google.cloud.datastore.Datastore;
+import com.google.cloud.datastore.DatastoreOptions;
+import com.google.cloud.datastore.Entity;
+import com.google.cloud.datastore.Query;
+import com.google.cloud.datastore.QueryResults;
+import com.google.cloud.datastore.StructuredQuery.CompositeFilter;
+import com.google.cloud.datastore.StructuredQuery.Filter;
+import com.google.cloud.datastore.StructuredQuery.PropertyFilter;
+
+public class OrFilterQuery {
+  public static void invoke() throws Exception {
+
+    // Instantiates a client
+    Datastore datastore = DatastoreOptions.getDefaultInstance().getService();
+    String propertyName = "description";
+
+    // Create the two filters
+    Filter orFilter =
+        CompositeFilter.or(
+            PropertyFilter.eq(propertyName, "Feed cats"),
+            PropertyFilter.eq(propertyName, "Buy milk"));
+
+    // Build the query
+    Query<Entity> query = Query.newEntityQueryBuilder().setKind("Task").setFilter(orFilter).build();
+
+    // Get the results back from Datastore
+    QueryResults<Entity> results = datastore.run(query);
+
+    if (!results.hasNext()) {
+      throw new Exception("query yielded no results");
+    }
+
+    while (results.hasNext()) {
+      Entity entity = results.next();
+      System.out.printf("Entity: %s%n", entity);
+    }
+  }
+}
+// [END datastore_query_filter_or]

samples/snippets/src/test/java/com/example/datastore/OrFilterQuerySampleIT.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.datastore;
+
+import com.example.datastore.filters.OrFilterQuery;
+import com.google.cloud.datastore.Datastore;
+import com.google.cloud.datastore.DatastoreOptions;
+import com.google.cloud.datastore.Entity;
+import com.google.cloud.datastore.Key;
+import com.rule.SystemsOutRule;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+@SuppressWarnings("checkstyle:abbreviationaswordinname")
+public class OrFilterQuerySampleIT {
+
+  private final Datastore datastore = DatastoreOptions.getDefaultInstance().getService();
+  private final String fieldName = "description";
+
+  private Key taskKey1;
+  private Key taskKey2;
+
+  @Rule public final SystemsOutRule systemsOutRule = new SystemsOutRule();
+
+  @Before
+  public void setUp() {
+    taskKey1 = datastore.newKeyFactory().setKind("Task").newKey("sampleTask");
+    Entity task1 = Entity.newBuilder(taskKey1).set(fieldName, "Buy milk").build();
+
+    taskKey2 = datastore.newKeyFactory().setKind("Task").newKey("sampleTask2");
+    Entity task2 = Entity.newBuilder(taskKey2).set(fieldName, "Feed cats").build();
+
+    datastore.put(task1);
+    datastore.put(task2);
+  }
+
+  @After
+  public void tearDown() {
+    datastore.delete(taskKey1);
+    datastore.delete(taskKey2);
+  }
+
+  @Test
+  public void testOrFilterQuery() throws Exception {
+    // Act
+    OrFilterQuery.invoke();
+
+    // Assert
+    systemsOutRule.assertContains("Entity");
+  }
+}