@Override
    public void mergeFrom(Input input, Collection<V> message) throws IOException
    {
        for (int number = input.readFieldNumber(this), i, nullCount;; number = input.readFieldNumber(this))
        {
            switch (number)
            {
                case 0:
                    return;
                case 1:
                    addValueFrom(input, message);
                    break;
                case 2:
                    for (nullCount = input.readUInt32(), i = 0; i < nullCount; i++)
                        message.add(null);
                    break;
                default:
                    throw new ProtostuffException("The collection was incorrectly serialized.");
            }
        }
    }
Transfers the value from the input to the output.
protostuff-collectionschema/src/main/java/io/protostuff/CollectionSchema.java