code: public synchronized void setDBDecoderFactory(@Nullable final DBDecoderFactory factory) {
          this.decoderFactory = factory;
  
          //Are we are using default factory?
          // If yes then we can use CollectibleDBObjectCodec directly, otherwise it will be wrapped.
          Decoder<DBObject> decoder = (factory == null || factory == DefaultDBDecoder.FACTORY)
                                      ? getDefaultDBObjectCodec()
                                      : new DBDecoderAdapter(factory.create(), this, getBufferPool());
          this.objectCodec = new CompoundDBObjectCodec(objectCodec.getEncoder(), decoder);
      }
docs: Set a custom decoder factory for this collection.  Set to null to use the default from MongoOptions.
  
  @param factory the factory to set.