Add a controller management api to get the polling time

Signed-off-by: SirWayne <dennis.melzer@bosch-si.com>

hawkbit-repository/src/main/java/org/eclipse/hawkbit/repository/ControllerManagement.java

@@ -33,7 +33,9 @@ import org.eclipse.hawkbit.repository.model.Target;
 import org.eclipse.hawkbit.repository.model.TargetInfo;
 import org.eclipse.hawkbit.repository.model.TargetUpdateStatus;
 import org.eclipse.hawkbit.repository.model.Target_;
+import org.eclipse.hawkbit.repository.model.TenantConfiguration;
 import org.eclipse.hawkbit.security.HawkbitSecurityProperties;
+import org.eclipse.hawkbit.tenancy.configuration.TenantConfigurationKey;
 import org.hibernate.validator.constraints.NotEmpty;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -86,6 +88,33 @@ public class ControllerManagement {
     @Autowired
     private HawkbitSecurityProperties securityProperties;
 
+    @Autowired
+    private TenantConfigurationRepository tenantConfigurationRepository;
+
+    @Autowired
+    private TenantConfigurationManagement tenantConfigurationManagement;
+
+    /**
+     * Retrieves all {@link SoftwareModule}s which are assigned to the given
+     * {@link DistributionSet}.
+     *
+     * @param distributionSet
+     *            the distribution set which should be assigned to the returned
+     *            {@link SoftwareModule}s
+     * @return a list of {@link SoftwareModule}s assigned to given
+     *         {@code distributionSet}
+     */
+    @PreAuthorize(SpringEvalExpressions.IS_CONTROLLER)
+    public String findPollingTime() {
+        final TenantConfigurationKey configurationKey = TenantConfigurationKey.POLLING_TIME_INTERVAL;
+        final Class<String> propertyType = String.class;
+        tenantConfigurationManagement.validateTenantConfigurationDataType(configurationKey, propertyType);
+        final TenantConfiguration tenantConfiguration = tenantConfigurationRepository
+                .findByKey(configurationKey.getKeyName());
+        return tenantConfigurationManagement
+                .buildTenantConfigurationValueByKey(configurationKey, propertyType, tenantConfiguration).getValue();
+    }
+
     /**
      * Refreshes the time of the last time the controller has been connected to
      * the server.

hawkbit-repository/src/main/java/org/eclipse/hawkbit/repository/TenantConfigurationManagement.java

@@ -85,16 +85,47 @@ public class TenantConfigurationManagement implements EnvironmentAware {
             + SpringEvalExpressions.IS_SYSTEM_CODE)
     public <T> TenantConfigurationValue<T> getConfigurationValue(final TenantConfigurationKey configurationKey,
             final Class<T> propertyType) {
+        validateTenantConfigurationDataType(configurationKey, propertyType);
 
+        final TenantConfiguration tenantConfiguration = tenantConfigurationRepository
+                .findByKey(configurationKey.getKeyName());
+
+        return buildTenantConfigurationValueByKey(configurationKey, propertyType, tenantConfiguration);
+    }
+
+    /**
+     * Validates the data type of the tenant configuration. If it is possible to
+     * cast to the given data type.
+     * 
+     * @param configurationKey
+     *            the key
+     * @param propertyType
+     *            the class
+     */
+    protected <T> void validateTenantConfigurationDataType(final TenantConfigurationKey configurationKey,
+            final Class<T> propertyType) {
         if (!configurationKey.getDataType().isAssignableFrom(propertyType)) {
             throw new TenantConfigurationValidatorException(
                     String.format("Cannot parse the database value of type %s into the type %s.",
                             configurationKey.getDataType(), propertyType));
         }
+    }
 
-        final TenantConfiguration tenantConfiguration = tenantConfigurationRepository
-                .findByKey(configurationKey.getKeyName());
-
+    /**
+     * Build the tenant configuration by the given key
+     * 
+     * @param configurationKey
+     *            the key
+     * @param propertyType
+     *            the property type
+     * @param tenantConfiguration
+     *            the configuration
+     * @return <null> if no default value is set and no database value available
+     *         or returns the tenant configuration value
+     */
+    protected <T> TenantConfigurationValue<T> buildTenantConfigurationValueByKey(
+            final TenantConfigurationKey configurationKey, final Class<T> propertyType,
+            final TenantConfiguration tenantConfiguration) {
         if (tenantConfiguration != null) {
             return TenantConfigurationValue.<T> builder().isGlobal(false).createdBy(tenantConfiguration.getCreatedBy())
                     .createdAt(tenantConfiguration.getCreatedAt())