Fix typo in javadoc of MongoOperations.stream.

Signed-off-by: Woojin Shin <wish.in@icloud.com>

Closes #4942

Author: wzyns

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

@@ -76,6 +76,7 @@
  * @author Thomas Darimont
  * @author Maninder Singh
  * @author Mark Paluch
+ * @author Woojin Shin
  */
 public interface MongoOperations extends FluentMongoOperations {
 
@@ -226,7 +227,7 @@ public <T> T execute(SessionCallback<T> action, Consumer<ClientSession> onComple
 	 * Executes the given {@link Query} on the entity collection of the specified {@code entityType} backed by a Mongo DB
 	 * {@link com.mongodb.client.FindIterable}.
 	 * <p>
-	 * Returns a {@link String} that wraps the Mongo DB {@link com.mongodb.client.FindIterable} that needs to be closed.
+	 * Returns a {@link Stream} that wraps the Mongo DB {@link com.mongodb.client.FindIterable} that needs to be closed.
 	 *
 	 * @param query the query class that specifies the criteria used to find a document and also an optional fields
 	 *          specification. Must not be {@literal null}.