introduce own interfaces for registering the currentTenantKeyGenerator

Signed-off-by: Michael Hirsch <michael.hirsch@bosch-si.com>

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

@@ -0,0 +1,40 @@
+/**
+ * Copyright (c) 2015 Bosch Software Innovations GmbH and others.
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.eclipse.hawkbit.repository.jpa;
+
+import org.springframework.cache.interceptor.KeyGenerator;
+import org.springframework.context.annotation.Bean;
+import org.springframework.stereotype.Service;
+
+/**
+ * Defines the interfaces to register the {@link KeyGenerator} as bean which is
+ * used by spring caching framework to resolve the key-generator. The
+ * key-generator must registered as bean so spring can resolve the key-generator
+ * by its name.
+ * 
+ * When using the {@link Service} annotation e.g. by {@link JpaSystemManagement}
+ * the bean registration must be declared by the interface due spring registers
+ * the bean by the implemented interfaces. So introduce a single interface for
+ * the {@link JpaSystemManagement} implementation to allow it to register the
+ * key-generator bean.
+ * 
+ */
+@FunctionalInterface
+public interface CurrentTenantCacheKeyGenerator {
+
+    /**
+     * Bean declaration to register a {@code currentTenantKeyGenerator} bean
+     * which is used by the caching framework.
+     * 
+     * @return the {@link KeyGenerator} to be used to cache the values of the
+     *         current used tenant in the {@link JpaSystemManagement}
+     */
+    @Bean
+    KeyGenerator currentTenantKeyGenerator();
+}

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

@@ -49,7 +49,7 @@ import org.springframework.validation.annotation.Validated;
 @Transactional(readOnly = true, isolation = Isolation.READ_UNCOMMITTED)
 @Validated
 @Service
-public class JpaSystemManagement implements SystemManagement {
+public class JpaSystemManagement implements CurrentTenantCacheKeyGenerator, SystemManagement {
     @Autowired
     private EntityManager entityManager;