class BuildTimestampValueSource extends AbstractValueSource {

    private final Date startTime;

    private final String format;

    private String formattedDate;

    public BuildTimestampValueSource(Date startTime, String format) {
        super(false);
        this.startTime = startTime;
        this.format = format;
    }

    public Object getValue(String expression) {<FILL_FUNCTION_BODY>}
}

        if ("build.timestamp".equals(expression) || "maven.build.timestamp".equals(expression)) {
            if (formattedDate == null && startTime != null) {
                formattedDate = new SimpleDateFormat(format).format(startTime);
            }

            return formattedDate;
        }

        return null;
    
<no_super_class>