private void writeWithoutNullTo(Output output, Collection<V> message) throws IOException
    {
        for (V value : message)
        {
            if (value != null)
                writeValueTo(output, 1, value, true);
        }
    }
Transfers the value from the input to the output.
protostuff-collectionschema/src/main/java/io/protostuff/CollectionSchema.java