@Override
    protected void transferValue(Pipe pipe, Input input, Output output, int number,
            boolean repeated) throws IOException
    {
        if (vPipeSchema == null)
        {
            throw new RuntimeException("No pipe schema for value: " +
                    vSchema.typeClass().getName());
        }

        output.writeObject(number, pipe, vPipeSchema, repeated);
    }
The pipe schema of the message value.
protostuff-collectionschema/src/main/java/io/protostuff/MessageMapSchema.java