driver-legacy/src/main/com/mongodb/DBCollection.java
public synchronized void setDBEncoderFactory(@Nullable final DBEncoderFactory factory) {
        this.encoderFactory = factory;

        //Are we are using default factory?
        // If yes then we can use CollectibleDBObjectCodec directly, otherwise it will be wrapped.
        Encoder<DBObject> encoder = (factory == null || factory == DefaultDBEncoder.FACTORY)
                                    ? getDefaultDBObjectCodec()
                                    : new DBEncoderFactoryAdapter(encoderFactory);
        this.objectCodec = new CompoundDBObjectCodec(encoder, objectCodec.getDecoder());
    }
public synchronized void setDBEncoderFactory(@Nullable final DBEncoderFactory factory) {
        this.encoderFactory = factory;

        //Are we are using default factory?
        // If yes then we can use CollectibleDBObjectCodec directly, otherwise it will be wrapped.
        Encoder<DBObject> encoder = (factory == null || factory == DefaultDBEncoder.FACTORY)
                                    ? getDefaultDBObjectCodec()
                                    : new DBEncoderFactoryAdapter(encoderFactory);
        this.objectCodec = new CompoundDBObjectCodec(encoder, objectCodec.getDecoder());
    }
Set a custom encoder factory for this collection.  Set to null to use the default from MongoOptions.

@param factory the factory to set.