@Override
    public void writeSInt64(int fieldNumber, long value, boolean repeated) throws IOException
    {
        generator.pushValue(schema, fieldNumber, new ImmutableLongValueImpl(value), repeated);
    }
Before serializing a message/object tied to a schema, this should be called. This also resets the internal state
of this output.
protostuff-msgpack/src/main/java/io/protostuff/MsgpackOutput.java