Fixed GenerationIdTest.generationIdTest(): test was failing precisely because the directory server's broker was not connected to a replication domain, hence it was impossible to add the changes to the changelogDB and then find them when querying the changelogDB.
GenerationIdTest.java:
Renamed assertConnectedToReplicationDomain() to waitConnectionToReplicationDomain().
LDAPReplicationDomain.java:
Removed uses of StringBuilder, relied on *Operation.toString() to do it for us.
ReplicationBroker.java:
Improved toString().
ReplicationTestCase.java:
Removed a wrong comment.
Used Assertions.assertThat().
ReplicationServerTest.java:
Removed a useless call to DirectoryServer.getSynchronizationProviders().