private static CharSequence generateEnumFieldNotPresentCondition(
        final int sinceVersion, final String enumName, final String indent)
    {
        if (0 == sinceVersion)
        {
            return "";
        }

        return String.format(
            indent + "        if (m_actingVersion < %1$d)\n" +
            indent + "        {\n" +
            indent + "            return %2$s::NULL_VALUE;\n" +
            indent + "        }\n\n",
            sinceVersion,
            enumName);
    }
\n");
        sb.append("     * The states in which a encoder/decoder/codec can live.\n");
        sb.append("     *\n");
        sb.append("     * <p>The state machine diagram below, encoded in the dot language, describes\n");
        sb.append("     * the valid state transitions according to the order in which fields may be\n");
        sb.append("     * accessed safely. Tools such as PlantUML and Graphviz can render it.\n");
        sb.append("     *\n");
        sb.append("     * <pre>{@code\n");
        fieldPrecedenceModel.generateGraph(sb, "     *   ");
        sb.append("     * }</pre>\n");
        sb.append("
sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/cpp/CppGenerator.java