Summary

This is the exact same issue that has been raised in JAVA-5134 for Kotlin driver, but affecting Java record codecs, which when decoding a nullable field when persisted field exists and contains null value (BSONType is NULL), the Java record codec could not handle the scenario correctly and will thrown a BsonInvalidOperationException.

Please provide the version of the driver. If applicable, please provide the MongoDB server version and topology (standalone, replica set, or sharded cluster).

Affected versions of Java driver: 4.11

How to Reproduce

Below test case reproduces the issue, included in https://github.com/mongodb/mongo-java-driver/pull/1223:

// Sample record

import javax.annotation.Nullable;

public record TestRecordWithNullableAnnotation (@BsonId ObjectId id, @Nullable String name) {
} 

// Sample test
@Test
public void testRecordWithStoredNulls() {
    var codec = createRecordCodec(TestRecordWithNullableAnnotation.class, Bson.DEFAULT_CODEC_REGISTRY);
    var identifier = new ObjectId();
    var testRecord = new TestRecordWithNullableAnnotation(identifier, null);

    var document = new BsonDocument("_id", new BsonObjectId(identifier))
            .append("name", new BsonNull());

    // when
    var decoded = codec.decode(new BsonDocumentReader(document), DecoderContext.builder().build());

    // then
    assertEquals(testRecord, decoded);
} 

Additional Background

I have already made a patch to fix this at https://github.com/mongodb/mongo-java-driver/pull/1223, which contains a fix in Java record codec and also a test verifying the patch is working.