Propagate time series options correctly.

This commit fixes an issue when creating a collection via MongoTemplate without passing on type information. In this case potential time series information was lost.

Closes #3984
Original pull request: #3990.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoTemplate.java

@@ -676,7 +676,7 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware,
 			@Nullable CollectionOptions collectionOptions) {
 
 		Assert.notNull(collectionName, "CollectionName must not be null!");
-		return doCreateCollection(collectionName, convertToDocument(collectionOptions));
+		return doCreateCollection(collectionName, convertToDocument(collectionOptions, Object.class));
 	}
 
 	/*

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/MongoTemplateUnitTests.java

@@ -2317,6 +2317,18 @@ public class MongoTemplateUnitTests extends MongoOperationsUnitTests {
 		verify(collection).countDocuments(any(Document.class), any());
 	}
 
+	@Test // GH-3984
+	void templatePassesOnTimeSeriesOptionsWhenNoTypeGiven() {
+
+		template.createCollection("time-series-collection", CollectionOptions.timeSeries("time_stamp"));
+
+		ArgumentCaptor<CreateCollectionOptions> options = ArgumentCaptor.forClass(CreateCollectionOptions.class);
+		verify(db).createCollection(any(), options.capture());
+
+		assertThat(options.getValue().getTimeSeriesOptions().toString())
+				.isEqualTo(new com.mongodb.client.model.TimeSeriesOptions("time_stamp").toString());
+	}
+
 	class AutogenerateableId {
 
 		@Id BigInteger id;