Introduce JavaClient for GWC Rest endpoints

[ahennr]

Title says it all. Herewith, for example, re-seed of a certain layer can be triggered easily (only in a given bound) in given services that modify the geometry of the cached layer.

Usage:

String username = "admin"; // GeoServer admin user
String password = "<<YOUR_GEOSERVER_PASSWORD>>";
String baseUrl = "http://geoserver.endpoint/geoserver/gwc/rest";

try (
    ShogunGwcManager manager = (ShogunGwcManager) ShogunClientBuilder.builder()
        .password(password)
        .username(username)
        .shogunServiceBaseUrl(baseUrl)
        .managerType(ShogunManagerType.GWC)
        .build()
) {
    Envelope bounds = new Envelope(600000,6000000.0,601000,6001000.0);
    String qualifiedLayerName = "SHOGUN:GEWAESSER";

    GwcSeedRequest gwcSeedRequest = new GwcSeedRequest(
        qualifiedLayerName,
        bounds,
        25832,
        "GRIDSETNAME",
        9,
        9,
        "image/png",
        SeedingType.reseed,
        4
    );

    boolean success = manager.startSeeding(gwcSeedRequest);
    if (success) {
        long t = System.currentTimeMillis();
        long end = t + 60000; // wait 1 minute
        while(System.currentTimeMillis() < end) {
            // check if caching is still running

            System.out.println("\nCurrently running tasks:");
            List<SeedingTaskStatus> currentTasks = manager.getRunningTasksForLayer(qualifiedLayerName);
            currentTasks.forEach(System.out::println);

            // wait 5 sec and check again
            Thread.sleep( 5000 );
        }
    }
}  catch (Exception e) {
    System.err.println(e);
}