Post-processing RenameByMapping failed Kafka MongoDB sink connector

Hello,
I set a sink connector to consume a kafka topic. I set a post-processing re-name but it failed :
nothing is written in the collection and no error so far in the log… I have no clue about it is.

Please can someone help?

Here is my connector config :

{
        "value.converter.schema.registry.url": "http://schema-registry:8080",
        "transforms.WrapKey.field": "_id",
        "transforms.WrapKey.type": "org.apache.kafka.connect.transforms.HoistField$Key",
        "name": "mongoDBSink_WinampArtists2",
        "connector.class": "com.mongodb.kafka.connect.MongoSinkConnector",
        "key.converter": "org.apache.kafka.connect.storage.StringConverter",
        "value.converter": "io.confluent.connect.avro.AvroConverter",
        "transforms": [
        "WrapKey"
        ],
        "topics": [
        "STR01VWARTISTS"
        ],
        "connection.uri": "mongodb://winamp:W0n4mp2020@mongodb:27017/winamp?authSource=admin",
        "database": "winamp",
        "collection": "WinampArtists2",
        "post.processor.chain": [
        "com.mongodb.kafka.connect.sink.processor.DocumentIdAdder",
        "com.mongodb.kafka.connect.sink.processor.field.renaming.RenameByMapping"
        ],
        "field.renamer.mapping": "[{\"oldName\":\"key.COUNTRYNAME\",\"newName\":\"CountryName\"},{\"oldName\":\"key.COUNTRYCODE\",\"newName\":\"CountryCode\"},{\"oldName\":\"key.IDALBUMS\",\"newName\":\"IDAlbums\"},{\"oldName\":\"key.GENRE\",\"newName\":\"Genre\"}]",
        "document.id.strategy": "com.mongodb.kafka.connect.sink.processor.id.strategy.ProvidedInKeyStrategy"
        }