Fix rollouts status cache eviction and NPE in UI (#530)

* Fix nullpointer in UI and rollout cache invalidation prob.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Sonar issue and util usage.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Evict cache on tenant delete.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

examples/hawkbit-device-simulator/src/main/java/org/eclipse/hawkbit/simulator/DeviceSimulatorUpdater.java

@@ -44,6 +44,7 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
 import org.springframework.stereotype.Service;
+import org.springframework.util.CollectionUtils;
 
 import com.google.common.eventbus.EventBus;
 import com.google.common.io.BaseEncoding;
@@ -105,7 +106,7 @@ public class DeviceSimulatorUpdater {
 
         device.setProgress(0.0);
 
-        if (modules == null || modules.isEmpty()) {
+        if (CollectionUtils.isEmpty(modules)) {
             device.setSwversion(swVersion);
         } else {
             device.setSwversion(

hawkbit-repository/hawkbit-repository-core/pom.xml

@@ -32,6 +32,10 @@
          <groupId>com.google.guava</groupId>
          <artifactId>guava</artifactId>
       </dependency>
+      <dependency>
+         <groupId>com.github.ben-manes.caffeine</groupId>
+         <artifactId>caffeine</artifactId>
+      </dependency>   
       <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-context-support</artifactId>

hawkbit-repository/hawkbit-repository-core/src/main/java/org/eclipse/hawkbit/repository/RolloutStatusCache.java

@@ -24,10 +24,10 @@ import org.eclipse.hawkbit.repository.model.RolloutGroup;
 import org.eclipse.hawkbit.repository.model.TotalTargetCountActionStatus;
 import org.eclipse.hawkbit.tenancy.TenantAware;
 import org.springframework.cache.Cache;
-import org.springframework.cache.guava.GuavaCacheManager;
+import org.springframework.cache.caffeine.CaffeineCacheManager;
 import org.springframework.context.event.EventListener;
 
-import com.google.common.cache.CacheBuilder;
+import com.github.benmanes.caffeine.cache.Caffeine;
 
 /**
  * Internal cache for Rollout status.
@@ -49,11 +49,11 @@ public class RolloutStatusCache {
     public RolloutStatusCache(final TenantAware tenantAware, final long size) {
         this.tenantAware = tenantAware;
 
-        final CacheBuilder<Object, Object> cacheBuilder = CacheBuilder.newBuilder().maximumSize(size);
+        final Caffeine<Object, Object> cacheBuilder = Caffeine.newBuilder().maximumSize(size);
-        final GuavaCacheManager guavaCacheManager = new GuavaCacheManager();
+        final CaffeineCacheManager caffeineCacheManager = new CaffeineCacheManager();
-        guavaCacheManager.setCacheBuilder(cacheBuilder);
+        caffeineCacheManager.setCaffeine(cacheBuilder);
 
-        this.cacheManager = new TenantAwareCacheManager(guavaCacheManager, tenantAware);
+        this.cacheManager = new TenantAwareCacheManager(caffeineCacheManager, tenantAware);
     }
 
     /**
@@ -174,8 +174,8 @@ public class RolloutStatusCache {
     }
 
     private Map<Long, List<TotalTargetCountActionStatus>> retrieveFromCache(final List<Long> ids, final Cache cache) {
-        return ids.stream().map(rolloutId -> cache.get(rolloutId, CachedTotalTargetCountActionStatus.class))
+        return ids.stream().map(id -> cache.get(id, CachedTotalTargetCountActionStatus.class)).filter(Objects::nonNull)
-                .filter(Objects::nonNull).collect(Collectors.toMap(CachedTotalTargetCountActionStatus::getRolloutId,
+                .collect(Collectors.toMap(CachedTotalTargetCountActionStatus::getId,
                         CachedTotalTargetCountActionStatus::getStatus));
     }
 
@@ -189,9 +189,8 @@ public class RolloutStatusCache {
         return cacheItem.getStatus();
     }
 
-    private void putIntoCache(final Long rolloutId, final List<TotalTargetCountActionStatus> status,
+    private void putIntoCache(final Long id, final List<TotalTargetCountActionStatus> status, final Cache cache) {
-            final Cache cache) {
+        cache.put(id, new CachedTotalTargetCountActionStatus(id, status));
-        cache.put(rolloutId, new CachedTotalTargetCountActionStatus(rolloutId, status));
     }
 
     private void putIntoCache(final Map<Long, List<TotalTargetCountActionStatus>> put, final Cache cache) {
@@ -201,20 +200,16 @@ public class RolloutStatusCache {
 
     @EventListener(classes = AbstractActionEvent.class)
     void invalidateCachedTotalTargetCountActionStatus(final AbstractActionEvent event) {
-        if (event.getRolloutId() == null) {
+        if (event.getRolloutId() != null) {
-            return;
+            final Cache cache = tenantAware.runAsTenant(event.getTenant(), () -> cacheManager.getCache(CACHE_RO_NAME));
-        }
-
-        Cache cache = tenantAware.runAsTenant(event.getTenant(), () -> cacheManager.getCache(CACHE_RO_NAME));
             cache.evict(event.getRolloutId());
-
-        if (event.getRolloutGroupId() == null) {
-            return;
         }
 
-        cache = tenantAware.runAsTenant(event.getTenant(), () -> cacheManager.getCache(CACHE_GR_NAME));
+        if (event.getRolloutGroupId() != null) {
+            final Cache cache = tenantAware.runAsTenant(event.getTenant(), () -> cacheManager.getCache(CACHE_GR_NAME));
             cache.evict(event.getRolloutGroupId());
         }
+    }
 
     @EventListener(classes = RolloutDeletedEvent.class)
     void invalidateCachedTotalTargetCountOnRolloutDelete(final RolloutDeletedEvent event) {
@@ -228,18 +223,28 @@ public class RolloutStatusCache {
         cache.evict(event.getEntityId());
     }
 
+    /**
+     * Evicts all caches for a given tenant. All caches under a certain tenant
+     * gets evicted.
+     *
+     * @param tenant
+     *            the tenant to evict caches
+     */
+    public void evictCaches(final String tenant) {
+        cacheManager.evictCaches(tenant);
+    }
+
     private static final class CachedTotalTargetCountActionStatus {
-        private final long rolloutId;
+        private final long id;
         private final List<TotalTargetCountActionStatus> status;
 
-        private CachedTotalTargetCountActionStatus(final long rolloutId,
+        private CachedTotalTargetCountActionStatus(final long id, final List<TotalTargetCountActionStatus> status) {
-                final List<TotalTargetCountActionStatus> status) {
+            this.id = id;
-            this.rolloutId = rolloutId;
             this.status = status;
         }
 
-        public long getRolloutId() {
+        public long getId() {
-            return rolloutId;
+            return id;
         }
 
         public List<TotalTargetCountActionStatus> getStatus() {

hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/JpaDistributionSetManagement.java

@@ -352,7 +352,7 @@ public class JpaDistributionSetManagement implements DistributionSetManagement {
             final DistributionSetFilter distributionSetFilter) {
         final List<Specification<JpaDistributionSet>> specList = buildDistributionSetSpecifications(
                 distributionSetFilter);
-        if (specList == null || specList.isEmpty()) {
+        if (CollectionUtils.isEmpty(specList)) {
             return null;
         }
         return distributionSetRepository.findOne(SpecificationsBuilder.combineWithAnd(specList));
@@ -667,7 +667,7 @@ public class JpaDistributionSetManagement implements DistributionSetManagement {
     private Page<JpaDistributionSet> findByCriteriaAPI(final Pageable pageable,
             final List<Specification<JpaDistributionSet>> specList) {
 
-        if (specList == null || specList.isEmpty()) {
+        if (CollectionUtils.isEmpty(specList)) {
             return distributionSetRepository.findAll(pageable);
         }
 

hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/JpaRolloutGroupManagement.java

@@ -53,6 +53,7 @@ import org.springframework.data.domain.PageImpl;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.jpa.domain.Specification;
 import org.springframework.transaction.annotation.Transactional;
+import org.springframework.util.CollectionUtils;
 import org.springframework.validation.annotation.Validated;
 
 /**
@@ -166,7 +167,7 @@ public class JpaRolloutGroupManagement implements RolloutGroupManagement {
         List<TotalTargetCountActionStatus> rolloutStatusCountItems = rolloutStatusCache
                 .getRolloutGroupStatus(rolloutGroupId);
 
-        if (rolloutStatusCountItems.isEmpty()) {
+        if (CollectionUtils.isEmpty(rolloutStatusCountItems)) {
             rolloutStatusCountItems = actionRepository.getStatusCountByRolloutGroupId(rolloutGroupId);
             rolloutStatusCache.putRolloutGroupStatus(rolloutGroupId, rolloutStatusCountItems);
         }

hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/JpaRolloutManagement.java

@@ -93,6 +93,7 @@ import org.springframework.transaction.PlatformTransactionManager;
 import org.springframework.transaction.TransactionException;
 import org.springframework.transaction.annotation.Propagation;
 import org.springframework.transaction.annotation.Transactional;
+import org.springframework.util.CollectionUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.util.concurrent.ListenableFuture;
 import org.springframework.validation.annotation.Validated;
@@ -177,7 +178,7 @@ public class JpaRolloutManagement extends AbstractRolloutManagement {
      */
     private Page<JpaRollout> findByCriteriaAPI(final Pageable pageable,
             final List<Specification<JpaRollout>> specList) {
-        if (specList == null || specList.isEmpty()) {
+        if (CollectionUtils.isEmpty(specList)) {
             return rolloutRepository.findAll(pageable);
         }
 
@@ -992,7 +993,7 @@ public class JpaRolloutManagement extends AbstractRolloutManagement {
 
         List<TotalTargetCountActionStatus> rolloutStatusCountItems = rolloutStatusCache.getRolloutStatus(rolloutId);
 
-        if (rolloutStatusCountItems.isEmpty()) {
+        if (CollectionUtils.isEmpty(rolloutStatusCountItems)) {
             rolloutStatusCountItems = actionRepository.getStatusCountByRolloutId(rolloutId);
             rolloutStatusCache.putRolloutStatus(rolloutId, rolloutStatusCountItems);
         }

hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/JpaSystemManagement.java

@@ -17,6 +17,7 @@ import java.util.stream.Collectors;
 import javax.persistence.EntityManager;
 
 import org.eclipse.hawkbit.cache.TenancyCacheManager;
+import org.eclipse.hawkbit.repository.RolloutStatusCache;
 import org.eclipse.hawkbit.repository.SystemManagement;
 import org.eclipse.hawkbit.repository.TenantStatsManagement;
 import org.eclipse.hawkbit.repository.jpa.configuration.Constants;
@@ -112,6 +113,9 @@ public class JpaSystemManagement implements CurrentTenantCacheKeyGenerator, Syst
     @Autowired
     private PlatformTransactionManager txManager;
 
+    @Autowired
+    private RolloutStatusCache rolloutStatusCache;
+
     @Override
     public SystemUsageReport getSystemUsageStatistics() {
 
@@ -219,6 +223,7 @@ public class JpaSystemManagement implements CurrentTenantCacheKeyGenerator, Syst
     public void deleteTenant(final String t) {
         final String tenant = t.toUpperCase();
         cacheManager.evictCaches(tenant);
+        rolloutStatusCache.evictCaches(tenant);
         tenantAware.runAsTenant(tenant, () -> {
             entityManager.setProperty(PersistenceUnitProperties.MULTITENANT_PROPERTY_DEFAULT, tenant);
             tenantMetaDataRepository.deleteByTenantIgnoreCase(tenant);

hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/JpaTargetFilterQueryManagement.java

@@ -41,6 +41,7 @@ import org.springframework.data.jpa.domain.Specifications;
 import org.springframework.retry.annotation.Backoff;
 import org.springframework.retry.annotation.Retryable;
 import org.springframework.transaction.annotation.Transactional;
+import org.springframework.util.CollectionUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.validation.annotation.Validated;
 
@@ -157,7 +158,7 @@ public class JpaTargetFilterQueryManagement implements TargetFilterQueryManageme
 
     private Page<JpaTargetFilterQuery> findTargetFilterQueryByCriteriaAPI(final Pageable pageable,
             final List<Specification<JpaTargetFilterQuery>> specList) {
-        if (specList == null || specList.isEmpty()) {
+        if (CollectionUtils.isEmpty(specList)) {
             return targetFilterQueryRepository.findAll(pageable);
         }
 

hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/JpaTargetManagement.java

@@ -67,6 +67,7 @@ import org.springframework.data.jpa.domain.Specification;
 import org.springframework.retry.annotation.Backoff;
 import org.springframework.retry.annotation.Retryable;
 import org.springframework.transaction.annotation.Transactional;
+import org.springframework.util.CollectionUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.validation.annotation.Validated;
 
@@ -317,7 +318,7 @@ public class JpaTargetManagement implements TargetManagement {
     }
 
     private Slice<Target> findByCriteriaAPI(final Pageable pageable, final List<Specification<JpaTarget>> specList) {
-        if (specList == null || specList.isEmpty()) {
+        if (CollectionUtils.isEmpty(specList)) {
             return convertPage(criteriaNoCountDao.findAll(pageable, JpaTarget.class), pageable);
         }
         return convertPage(
@@ -326,7 +327,7 @@ public class JpaTargetManagement implements TargetManagement {
     }
 
     private Long countByCriteriaAPI(final List<Specification<JpaTarget>> specList) {
-        if (specList == null || specList.isEmpty()) {
+        if (CollectionUtils.isEmpty(specList)) {
             return targetRepository.count();
         }
 

hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/rsql/RSQLUtility.java

@@ -43,6 +43,7 @@ import org.slf4j.LoggerFactory;
 import org.springframework.beans.SimpleTypeConverter;
 import org.springframework.beans.TypeMismatchException;
 import org.springframework.data.jpa.domain.Specification;
+import org.springframework.util.CollectionUtils;
 
 import cz.jirutka.rsql.parser.RSQLParser;
 import cz.jirutka.rsql.parser.RSQLParserException;
@@ -169,7 +170,7 @@ public final class RSQLUtility {
                     virtualPropertyReplacer);
             final List<Predicate> accept = rootNode.<List<Predicate>, String> accept(jpqQueryRSQLVisitor);
 
-            if (accept != null && !accept.isEmpty()) {
+            if (!CollectionUtils.isEmpty(accept)) {
                 return cb.and(accept.toArray(new Predicate[accept.size()]));
             }
             return cb.conjunction();
@@ -652,7 +653,7 @@ public final class RSQLUtility {
             final List<Predicate> childs = new ArrayList<>();
             for (final Node node2 : children) {
                 final List<Predicate> accept = node2.accept(this);
-                if (accept != null && !accept.isEmpty()) {
+                if (!CollectionUtils.isEmpty(accept)) {
                     childs.addAll(accept);
                 } else {
                     LOGGER.debug("visit logical node children but could not parse it, ignoring {}", node2);

hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/rsql/RsqlParserValidationOracle.java

@@ -34,6 +34,7 @@ import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.orm.jpa.JpaSystemException;
+import org.springframework.util.CollectionUtils;
 
 import com.google.common.collect.ArrayListMultimap;
 import com.google.common.collect.Multimap;
@@ -149,7 +150,7 @@ public class RsqlParserValidationOracle implements RsqlValidationOracle {
             final int currentTokenEndColumn, final int[] is) {
         for (final int i : is) {
             final Collection<String> tokenImage = TokenDescription.getTokenImage(i);
-            if (tokenImage != null && !tokenImage.isEmpty()) {
+            if (!CollectionUtils.isEmpty(tokenImage)) {
                 tokenImage.forEach(image -> listTokens.add(new SuggestToken(currentTokenEndColumn + 1,
                         nextTokenBeginColumn + image.length(), null, image)));
             }
@@ -164,8 +165,8 @@ public class RsqlParserValidationOracle implements RsqlValidationOracle {
                     .of(FieldNameDescription.toTopSuggestToken(nextTokenBeginColumn - currentTokenImageName.length(),
                             nextTokenBeginColumn + currentTokenImageName.length(), currentTokenImageName));
         } else if (shouldSuggestDotToken(currentTokenImageName, containsDot)) {
-            return Optional.of(
+            return Optional
-                    Arrays.asList(new SuggestToken(currentTokenEndColumn, nextTokenBeginColumn + 1, null, ".")));
+                    .of(Arrays.asList(new SuggestToken(currentTokenEndColumn, nextTokenBeginColumn + 1, null, ".")));
         } else if (shouldSuggestSubTokenFieldNames(currentTokenImageName, containsDot)) {
             return handleSubtokenSuggestion(currentTokenImageName, nextTokenBeginColumn);
         }
@@ -222,7 +223,7 @@ public class RsqlParserValidationOracle implements RsqlValidationOracle {
             builder = builder.substring(0, builder.lastIndexOf("Was expecting"));
         }
 
-        if (expectedTokens != null && !expectedTokens.isEmpty()) {
+        if (!CollectionUtils.isEmpty(expectedTokens)) {
             final StringBuilder tokens = new StringBuilder();
             expectedTokens.stream().forEach(value -> tokens.append(value.getSuggestion() + ","));
             builder = builder.concat("Was expecting :" + tokens.toString().substring(0, tokens.length() - 1));

hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/common/CommonDialogWindow.java

@@ -19,7 +19,6 @@ import java.util.Objects;
 import java.util.Set;
 import java.util.stream.Collectors;
 
-import org.springframework.util.StringUtils;
 import org.eclipse.hawkbit.ui.artifacts.smtable.SoftwareModuleAddUpdateWindow;
 import org.eclipse.hawkbit.ui.components.SPUIComponentProvider;
 import org.eclipse.hawkbit.ui.decorators.SPUIButtonStyleNoBorderWithIcon;
@@ -28,6 +27,8 @@ import org.eclipse.hawkbit.ui.management.targettable.TargetAddUpdateWindowLayout
 import org.eclipse.hawkbit.ui.utils.SPUIStyleDefinitions;
 import org.eclipse.hawkbit.ui.utils.UIComponentIdProvider;
 import org.eclipse.hawkbit.ui.utils.VaadinMessageSource;
+import org.springframework.util.CollectionUtils;
+import org.springframework.util.StringUtils;
 import org.vaadin.hene.flexibleoptiongroup.FlexibleOptionGroupItemComponent;
 
 import com.google.common.base.Strings;
@@ -359,7 +360,7 @@ public class CommonDialogWindow extends Window {
     }
 
     private static Object emptyToNull(final Collection<?> c) {
-        return (c == null || c.isEmpty()) ? null : c;
+        return CollectionUtils.isEmpty(c) ? null : c;
     }
 
     private boolean hasNullValidator(final Component component) {

hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/common/detailslayout/SoftwareModuleDetailsTable.java

@@ -28,6 +28,7 @@ import org.eclipse.hawkbit.ui.utils.UINotification;
 import org.eclipse.hawkbit.ui.utils.VaadinMessageSource;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.util.CollectionUtils;
 import org.vaadin.spring.events.EventBus;
 
 import com.vaadin.data.Item;
@@ -156,10 +157,10 @@ public class SoftwareModuleDetailsTable extends Table {
             final Set<SoftwareModuleType> swModuleMandatoryTypes = distributionSet.getType().getMandatoryModuleTypes();
             final Set<SoftwareModuleType> swModuleOptionalTypes = distributionSet.getType().getOptionalModuleTypes();
 
-            if (swModuleMandatoryTypes != null && !swModuleMandatoryTypes.isEmpty()) {
+            if (!CollectionUtils.isEmpty(swModuleMandatoryTypes)) {
                 swModuleMandatoryTypes.forEach(swModule -> setSwModuleProperties(swModule, true, distributionSet));
             }
-            if (swModuleOptionalTypes != null && !swModuleOptionalTypes.isEmpty()) {
+            if (!CollectionUtils.isEmpty(swModuleOptionalTypes)) {
                 swModuleOptionalTypes.forEach(swModule -> setSwModuleProperties(swModule, false, distributionSet));
             }
         }

hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/common/detailslayout/SoftwareModuleMetadatadetailslayout.java

@@ -22,6 +22,7 @@ import org.eclipse.hawkbit.ui.utils.SPUIStyleDefinitions;
 import org.eclipse.hawkbit.ui.utils.UIComponentIdProvider;
 import org.eclipse.hawkbit.ui.utils.VaadinMessageSource;
 import org.springframework.data.domain.PageRequest;
+import org.springframework.util.CollectionUtils;
 
 import com.vaadin.data.Item;
 import com.vaadin.data.util.IndexedContainer;
@@ -99,7 +100,7 @@ public class SoftwareModuleMetadatadetailslayout extends Table {
                 .findSoftwareModuleMetadataBySoftwareModuleId(selectedSWModuleId,
                         new PageRequest(0, MAX_METADATA_QUERY))
                 .getContent();
-        if (null != swMetadataList && !swMetadataList.isEmpty()) {
+        if (!CollectionUtils.isEmpty(swMetadataList)) {
             swMetadataList.forEach(this::setSWMetadataProperties);
         }
     }

hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/common/grid/AbstractGrid.java

@@ -606,11 +606,14 @@ public abstract class AbstractGrid<T extends Indexed> extends Grid implements Re
         @Override
         public String getStyle(final CellReference cellReference) {
 
-            if (Arrays.stream(center).anyMatch(o -> Objects.equals(o, cellReference.getPropertyId()))) {
+            if (center != null
+                    && Arrays.stream(center).anyMatch(o -> Objects.equals(o, cellReference.getPropertyId()))) {
                 return "centeralign";
-            } else if (Arrays.stream(right).anyMatch(o -> Objects.equals(o, cellReference.getPropertyId()))) {
+            } else if (right != null
+                    && Arrays.stream(right).anyMatch(o -> Objects.equals(o, cellReference.getPropertyId()))) {
                 return "rightalign";
-            } else if (Arrays.stream(left).anyMatch(o -> Objects.equals(o, cellReference.getPropertyId()))) {
+            } else if (left != null
+                    && Arrays.stream(left).anyMatch(o -> Objects.equals(o, cellReference.getPropertyId()))) {
                 return "leftalign";
             }
             return null;

hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/distributions/disttype/CreateUpdateDistSetTypeLayout.java

@@ -38,6 +38,7 @@ import org.eclipse.hawkbit.ui.utils.UIComponentIdProvider;
 import org.eclipse.hawkbit.ui.utils.UINotification;
 import org.eclipse.hawkbit.ui.utils.VaadinMessageSource;
 import org.springframework.data.domain.PageRequest;
+import org.springframework.util.CollectionUtils;
 import org.vaadin.addons.lazyquerycontainer.BeanQueryFactory;
 import org.vaadin.addons.lazyquerycontainer.LazyQueryContainer;
 import org.vaadin.spring.events.EventBus.UIEventBus;
@@ -388,7 +389,7 @@ public class CreateUpdateDistSetTypeLayout extends CreateUpdateTypeLayout<Distri
         final String typeKeyValue = HawkbitCommonUtil.trimAndNullIfEmpty(typeKey.getValue());
         final String typeDescValue = HawkbitCommonUtil.trimAndNullIfEmpty(tagDesc.getValue());
         final List<Long> itemIds = (List<Long>) selectedTable.getItemIds();
-        if (null != typeNameValue && null != typeKeyValue && null != itemIds && !itemIds.isEmpty()) {
+        if (null != typeNameValue && null != typeKeyValue && !CollectionUtils.isEmpty(itemIds)) {
 
             final List<Long> mandatory = itemIds.stream()
                     .filter(itemId -> isMandatoryModuleType(selectedTable.getItem(itemId)))
@@ -429,8 +430,8 @@ public class CreateUpdateDistSetTypeLayout extends CreateUpdateTypeLayout<Distri
         final DistributionSetTypeUpdate update = entityFactory.distributionSetType().update(existingType.getId())
                 .description(tagDesc.getValue())
                 .colour(ColorPickerHelper.getColorPickedString(getColorPickerLayout().getSelPreview()));
-        if (distributionSetTypeManagement.countDistributionSetsByType(existingType.getId()) <= 0 && null != itemIds
+        if (distributionSetTypeManagement.countDistributionSetsByType(existingType.getId()) <= 0
-                && !itemIds.isEmpty()) {
+                && !CollectionUtils.isEmpty(itemIds)) {
 
             update.mandatory(itemIds.stream().filter(itemId -> isMandatoryModuleType(selectedTable.getItem(itemId)))
                     .collect(Collectors.toList()))

hawkbit-ui/src/main/java/org/eclipse/hawkbit/ui/distributions/footer/DistributionsConfirmationWindowLayout.java

@@ -38,6 +38,7 @@ import org.eclipse.hawkbit.ui.utils.SPUILabelDefinitions;
 import org.eclipse.hawkbit.ui.utils.SPUIStyleDefinitions;
 import org.eclipse.hawkbit.ui.utils.UIComponentIdProvider;
 import org.eclipse.hawkbit.ui.utils.VaadinMessageSource;
+import org.springframework.util.CollectionUtils;
 import org.vaadin.spring.events.EventBus.UIEventBus;
 import org.vaadin.spring.events.EventScope;
 import org.vaadin.spring.events.annotation.EventBusListenerMethod;
@@ -324,8 +325,7 @@ public class DistributionsConfirmationWindowLayout extends AbstractConfirmationW
 
     private void discardSoftwareTypeDelete(final String discardSWModuleType, final Object itemId,
             final ConfirmationTab tab) {
-        if (null != manageDistUIState.getSelectedDeleteSWModuleTypes()
+        if (!CollectionUtils.isEmpty(manageDistUIState.getSelectedDeleteSWModuleTypes())
-                && !manageDistUIState.getSelectedDeleteSWModuleTypes().isEmpty()
                 && manageDistUIState.getSelectedDeleteSWModuleTypes().contains(discardSWModuleType)) {
             manageDistUIState.getSelectedDeleteSWModuleTypes().remove(discardSWModuleType);
         }
@@ -420,8 +420,7 @@ public class DistributionsConfirmationWindowLayout extends AbstractConfirmationW
     private void discardDistDelete(final Button.ClickEvent event, final Object itemId, final ConfirmationTab tab) {
 
         final DistributionSetIdName distId = (DistributionSetIdName) ((Button) event.getComponent()).getData();
-        if (null != manageDistUIState.getDeletedDistributionList()
+        if (!CollectionUtils.isEmpty(manageDistUIState.getDeletedDistributionList())
-                && !manageDistUIState.getDeletedDistributionList().isEmpty()
                 && manageDistUIState.getDeletedDistributionList().contains(distId)) {
             manageDistUIState.getDeletedDistributionList().remove(distId);
         }
@@ -509,8 +508,7 @@ public class DistributionsConfirmationWindowLayout extends AbstractConfirmationW
 
     private void discardDistTypeDelete(final String discardDSType, final Object itemId, final ConfirmationTab tab) {
 
-        if (null != manageDistUIState.getSelectedDeleteDistSetTypes()
+        if (!CollectionUtils.isEmpty(manageDistUIState.getSelectedDeleteDistSetTypes())
-                && !manageDistUIState.getSelectedDeleteDistSetTypes().isEmpty()
                 && manageDistUIState.getSelectedDeleteDistSetTypes().contains(discardDSType)) {
             manageDistUIState.getSelectedDeleteDistSetTypes().remove(discardDSType);
         }