Add test for CompositeDateHistogramAggregationSource

Signed-off-by: Fabien Crespel <[email protected]>

java-client/src/test/java/org/opensearch/client/opensearch/_types/aggregations/CompositeDateHistogramAggregationSourceTest.java

@@ -0,0 +1,23 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.client.opensearch._types.aggregations;
+
+import org.junit.Test;
+import org.opensearch.client.opensearch.model.ModelTestCase;
+
+public class CompositeDateHistogramAggregationSourceTest extends ModelTestCase {
+
+    @Test
+    public void testSerializeSpecificFields() {
+        String json = "{\"calendar_interval\":\"1d\",\"fixed_interval\":\"1d\",\"offset\":1,\"time_zone\":\"+01:00\"}";
+        CompositeDateHistogramAggregationSource aggregation = fromJson(json, CompositeDateHistogramAggregationSource._DESERIALIZER);
+        assertEquals(json, toJson(aggregation));
+    }
+
+}