DATAMONGO-2427 - Upgrade to MongoDB Driver 4.0 Snapshot

[christophstrobl]

This ⚠️ breaking ⚠️ change switches to the MongoDB 4.0 driver and introduces configuration options for com.mongodb.client.MongoClient.
The XML namespace changes from client-options to client-settings and removes already deprecated elements and attributes.

Imports are switched from single artifact uber jar (mongo-java-driver) to split imports for driver-core, -sync and -reactivestreams (one of the latter 2 required).

API deprecations from previous versions have now been removed.

Changed Java API

Type	Comment
MongoClientFactoryBean	Creates com.mongodb.client.MongoClient instead of com.mongodb.MongoClient. Uses MongoClientSettings instead of MongoClientOptions.
MongoDataIntegrityViolationException	Uses WriteConcernResult instead of WriteResult.
BulkOperationException	Uses MongoBulkWriteException and com.mongodb.bulk.BulkWriteError instead of BulkWriteException and com.mongodb.BulkWriteError
ReactiveMongoClientFactoryBean	Uses com.mongodb.MongoClientSettings instead of com.mongodb.async.client.MongoClientSettings
ReactiveMongoClientSettingsFactoryBean	Now produces com.mongodb.MongoClientSettings instead of com.mongodb.async.client.MongoClientSettings

Removed Java API

2.x	Replacement in 3.x	Comment
MongoClientOptionsFactoryBean	MongoClientSettingsFactoryBean	Creating a com.mongodb.MongoClientSettings.
AbstractMongoConfiguration	AbstractMongoClientConfiguration (Available since 2.1)	Using com.mongodb.client.MongoClient.
MongoDbFactory#getLegacyDb()	-	-
SimpleMongoDbFactory	SimpleMongoClientDbFactory (Available since 2.1)	-
MapReduceOptions#getOutputType()	MapReduceOptions#getMapReduceAction()	Returns MapReduceAction instead of MapReduceCommand.OutputType.
Meta|Query maxScan & snapshot	-	-

Changed XML Namespace Elements and Attributes:

Element / Attribute	2.x	3.x
<mongo:mongo-client />	Used to create a com.mongodb.MongoClient	Now exposes a com.mongodb.client.MongoClient
<mongo:mongo-client replica-set="..." />	Was a comma delimited list of replica set members (host/port)	Now defines the replica set name. Use <mongo:client-settings cluster-hosts="..." /> instead
<mongo:db-factory writeConcern="..." />	NONE, NORMAL, SAFE, FSYNC_SAFE, REPLICAS_SAFE, MAJORITY	W1, W2, W3, UNAKNOWLEDGED, AKNOWLEDGED, JOURNALED, MAJORITY

Removed XML Namespace Elements and Attributes:

Element / Attribute	Replacement in 3.x	Comment
<mongo:db-factory mongo-ref="..." />	<mongo:db-factory mongo-client-ref="..." />	Referencing a com.mongodb.client.MongoClient.
<mongo:mongo-client credentials="..." />	<mongo:mongo-client credential="..." />	Single authentication data instead of list.
<mongo:client-options />	<mongo:client-settings />	See com.mongodb.MongoClientSettings for details.

New XML Namespace Elements and Attributes:

Element	Comment
<mongo:db-factory mongo-client-ref="..." />	Replacement for <mongo:db-factory mongo-ref="..." />
<mongo:db-factory connection-string="..." />	Replacement for uri and client-uri.
<mongo:mongo-client connection-string="..." />	Replacement for uri and client-uri.
<mongo:client-settings />	Namespace element for com.mongodb.MongoClientSettings.

UUID Type Changes

The MongoDB UUID representation can now be configured with different formats.
This has to be done via MongoClientSettings as shown in the snippet below.

class Config extends AbstractMongoClientConfiguration {

    @Override
    public void configureClientSettings(MongoClientSettings.Builder builder) {
        builder.uuidRepresentation(UuidRepresentation.STANDARD);
    }

    // ...
}

---

Supersedes: #812

[mp911de]

That's merged and polished now.