In MongoDB Java Driver, these are two main package: org.bson and com.mongodb. com.mongodb depend org.bson. but now In org.bson package, those file depend com.mongodb:
org.bson.io.OutputBuffer use: com.mongodb.util.Util.toHex
org.bson.BasicBSONObject use: com.mongodb.util.JSON.serialize
org.bson.BSONEncoder use: com.mongodb.DBRefBase and com.mongodb.util.MyAsserts.assertEquals