Hello,

it seems that the java documentation was not generated for version 3.8. 

For example in MongoCollection interface : 

The javadoc does not contains new methods like  countDocuments

http://mongodb.github.io/mongo-java-driver/3.8/javadoc/com/mongodb/client/MongoCollection.html

And this method exists in java class com.mongodb.client.MongoCollection :

* @return the number of documents in the collection
 * @since 3.8
 */
 long countDocuments();