Fixes return in Javadoc.

Closes: #4255

Author: michaelkrog

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

@@ -139,6 +139,7 @@
  * @author Yadhukrishna S Pai
  * @author Anton Barkan
  * @author Bartłomiej Mazur
+ * @author Michael Krog
  */
 public class MongoTemplate implements MongoOperations, ApplicationContextAware, IndexOperationsProvider {
 
@@ -2346,7 +2347,7 @@ private CreateCollectionOptions getCreateCollectionOptions(Document document) {
 	 * @param query the query document that specifies the criteria used to find a record.
 	 * @param fields the document that specifies the fields to be returned.
 	 * @param entityClass the parameterized type of the returned list.
-	 * @return the {@link List} of converted objects.
+	 * @return the converted object or null if none exists.
 	 */
 	protected <T> T doFindOne(String collectionName, Document query, Document fields, Class<T> entityClass) {
 		return doFindOne(collectionName, query, fields, CursorPreparer.NO_OP_PREPARER, entityClass);
@@ -2361,7 +2362,7 @@ protected <T> T doFindOne(String collectionName, Document query, Document fields
 	 * @param fields the document that specifies the fields to be returned.
 	 * @param entityClass the parameterized type of the returned list.
 	 * @param preparer the preparer used to modify the cursor on execution.
-	 * @return the {@link List} of converted objects.
+	 * @return the converted object or null if none exists.
 	 * @since 2.2
 	 */
 	@SuppressWarnings("ConstantConditions")