Feature fixed timezone (#824)

* Fix typo
* Set fixedTimeZone via properties
* Fix Sonar findings
* Fix review findings
* Rename variable
* Fix logic

Signed-off-by: Jeroen Laverman <jeroen.laverman@bosch-si.com>

hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/AbstractHawkbitUI.java

@@ -16,6 +16,7 @@ import org.eclipse.hawkbit.ui.menu.DashboardMenuItem;
 import org.eclipse.hawkbit.ui.push.EventPushStrategy;
 import org.eclipse.hawkbit.ui.themes.HawkbitTheme;
 import org.eclipse.hawkbit.ui.utils.HawkbitCommonUtil;
+import org.eclipse.hawkbit.ui.utils.SPDateTimeUtil;
 import org.eclipse.hawkbit.ui.utils.SpringContextHelper;
 import org.eclipse.hawkbit.ui.utils.VaadinMessageSource;
 import org.slf4j.Logger;
@@ -121,6 +122,7 @@ public abstract class AbstractHawkbitUI extends UI implements DetachListener {
         rootLayout.setSizeFull();
 
         HawkbitCommonUtil.initLocalization(this, uiProperties.getLocalization(), i18n);
+        SPDateTimeUtil.initializeFixedTimeZoneProperty(uiProperties.getFixedTimeZone());
 
         dashboardMenu.init();
         dashboardMenu.setResponsive(true);

hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/UiProperties.java

@@ -25,6 +25,8 @@ public class UiProperties implements Serializable {
 
     private boolean gravatar;
 
+    private String fixedTimeZone;
+
     private final Localization localization = new Localization();
 
     private final Links links = new Links();
@@ -43,6 +45,15 @@ public class UiProperties implements Serializable {
         this.gravatar = gravatar;
     }
 
+    public String getFixedTimeZone() {
+        return fixedTimeZone;
+    }
+
+    public void setFixedTimeZone(final String fixedTimeZone) {
+        this.fixedTimeZone = fixedTimeZone;
+    }
+
+
     /**
      * Localization information
      */

hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/utils/SPDateTimeUtil.java

@@ -19,6 +19,7 @@ import org.eclipse.hawkbit.repository.model.BaseEntity;
 
 import com.google.common.collect.Maps;
 import com.vaadin.server.WebBrowser;
+import org.springframework.util.StringUtils;
 
 /**
  * Common Util to get date/time related information.
@@ -27,6 +28,7 @@ public final class SPDateTimeUtil {
 
     private static final String DURATION_FORMAT = "y','M','d','H','m','s";
     private static final Map<Integer, CalendarI18N> DURATION_I18N = Maps.newHashMapWithExpectedSize(6);
+    private static String fixedTimeZoneProperty;
 
     static {
         DURATION_I18N.put(0, CalendarI18N.YEAR);
@@ -41,12 +43,29 @@ public final class SPDateTimeUtil {
 
     }
 
+
     /**
-     * Get browser time zone.
+     * Set fixed UI timezone
+     *
+     * @param fixedTimeZoneProperty
+     *      time zone e.g. Europe/Berlin. If time zone is unknown, it will default to GMT
+     */
+    public static void initializeFixedTimeZoneProperty(String fixedTimeZoneProperty) {
+        SPDateTimeUtil.fixedTimeZoneProperty = fixedTimeZoneProperty;
+    }
+
+    /**
+     * Get browser time zone or fixed time zone if configured
      *
      * @return TimeZone
      */
     public static TimeZone getBrowserTimeZone() {
+
+
+        if (!StringUtils.isEmpty(fixedTimeZoneProperty)) {
+            return TimeZone.getTimeZone(fixedTimeZoneProperty);
+        }
+
         final WebBrowser webBrowser = com.vaadin.server.Page.getCurrent().getWebBrowser();
         final String[] timeZones = TimeZone.getAvailableIDs(webBrowser.getRawTimezoneOffset());
         TimeZone tz = TimeZone.getDefault();