A memory-efficient message handler for obtaining line counts for a file

RunStats.java

@JsonPropertyOrder(value = { "run", "runParameters", "fileStatistics", "runSummary" })
public class RunStats {

    public static final String TYPE = "type";
    public static final String START_DATE = "start";
    public static final String END_DATE = "end";

    @JsonProperty("run")
    private Integer run;

    @JsonProperty("runParameters")
    private final Map<String, Object> runParameters = new LinkedHashMap<>();

    @JsonProperty("fileStatistics")
    private final Map<String, Long> fileStatistics = new HashMap<>();

    @JsonProperty("runSummary")
    private final Map<String, Long> runSummary = new LinkedHashMap<>();

    public RunStats(Integer run) {
        this.run = run;
    }

    public void addFile(String filename, Long lineCount) {
        fileStatistics.put(filename, lineCount);
    }

    public void addInputParameter(String parameterName, Object parameterValue) {
        runParameters.put(parameterName, parameterValue);
    }

    public void addSummary(String status, Long lineCount) {
        Long currentCount = runSummary.get(status);
        if (currentCount == null) {
            runSummary.put(status, lineCount);
        } else {
            runSummary.put(status, currentCount + lineCount);
        }
    }

    public Integer getRun() {
        return run;
    }

    public Map<String, Long> getFileStatistics() {
        return Collections.unmodifiableMap(fileStatistics);
    }

    public Map<String, Object> getRunParameters() {
        return Collections.unmodifiableMap(runParameters);
    }

    public Map<String, Long> getRunSummary() {
        return Collections.unmodifiableMap(runSummary);
    }
}

RunStatsHandler.java

protected static class RunStatsHandler extends AbstractMessageHandler {

        // Memory efficient routine, @see http://www.baeldung.com/java-read-lines-large-file
        @Override
        protected void handleMessageInternal(Message<?> message) throws Exception {
            RunStats runStats = (RunStats) message.getHeaders().get("runStats");
            if (runStats != null) {
                File compressedFile = (File) message.getPayload();
                String filename = compressedFile.getCanonicalPath();
                LongAdder lineCount = new LongAdder();
                // Streams and Scanner implement java.lang.AutoCloseable
                try (   InputStream fs = new FileInputStream(compressedFile);
                        InputStream gzfs = new GZIPInputStream(fs);
                        Scanner sc = new Scanner(gzfs, "UTF-8");
                    ) {
                    while (sc.hasNextLine()) {
                        sc.nextLine();
                        lineCount.increment();
                    }
                    // note that Scanner suppresses exceptions
                    if (sc.ioException() != null) {
                        throw sc.ioException();
                    }
                    runStats.addFile(filename, lineCount.longValue());
                }
            }
        }

    }