how to solve java.lang.NullPointerException in debezium mongo db source connector?

Question

I am using debezium mongo DB source connector. it works well for create/update but for delete, I want the complete document to filter in target DB. for that I configured my connector with handling mode

"transforms.unwrap.delete.handling.mode" : "rewrite",

but it gives error (screenshot attached)

"Caused by: java.lang.NullPointerException" 

though it works well when I do

"transforms.unwrap.delete.handling.mode" : "drop",

but in this case, i get null in value.

I tried below transforms.unwrap.type but get the same result

1. "transforms.unwrap.type" : "io.debezium.transforms.UnwrapFromEnvelope",
2. "transforms.unwrap.type" : "io.debezium.connector.mongodb.transforms.UnwrapFromMongoDbEnvelope",
3. "transforms.unwrap.type" : "io.debezium.transforms.ExtractNewRecordState",

is there any way to get the complete document in the case of delete instead on null

please find attached screenshot of error and complete configuration of connector

    {
    "name": "inventory-mongo-connector",
    "config": {
         "connector.class" : "io.debezium.connector.mongodb.MongoDbConnector",
        "tasks.max" : "1",
        "mongodb.hosts" : "XXXXX",
        "mongodb.name" : "YYYY",
        "mongodb.user" : "ZZZZ",
        "mongodb.password" : "TTTTT",
        "database.whitelist" : "maindb",
        "collection.whitelist":"maindb.collection1,maindb.collection2",
        "database.history.kafka.bootstrap.servers" : "kafka:9092",
        "transforms" : "unwrap",  
        "transforms.unwrap.type" : "io.debezium.transforms.UnwrapFromEnvelope",
        "transforms.unwrap.drop.tombstones" : "false",
        "transforms.unwrap.delete.handling.mode" : "rewrite",
        "transforms.unwrap.operation.header" : "true"
    }
}