private String formattedTimestamp;

    public MavenBuildTimestamp() {
        this(Instant.now());
    }

    public MavenBuildTimestamp(Instant time) {
        this(time, DEFAULT_BUILD_TIMESTAMP_FORMAT);
    }

    public MavenBuildTimestamp(Instant time, Map<String, String> properties) {

        }

        @Override
        public Object getValue(String expression) {
            if ("build.timestamp".equals(expression) || "maven.build.timestamp".equals(expression)) {
                return new MavenBuildTimestamp(startTime, properties).formattedTimestamp();
            }
            return null;
        }
    }