Use 'everyChange' as default strategy for JDBC persistence (#8841)

Signed-off-by: Christoph Weitkamp <github@christophweitkamp.de>

bundles/org.openhab.persistence.jdbc/README.md

@@ -60,7 +60,7 @@ This service can be configured in the file `services/jdbc.cfg`.
 | tableUseRealItemNames     | `false`                                                      |    No     | table name prefix generation.  When set to `true`, real item names are used for table names and `tableNamePrefix` is ignored.  When set to `false`, the `tableNamePrefix` is used to generate table names with sequential numbers. |
 | tableIdDigitCount         | 4                                                            |    No     | when `tableUseRealItemNames` is `false` and thus table names are generated sequentially, this controls how many zero-padded digits are used in the table name.  With the default of 4, the first table name will end with `0001`. For migration from the MySQL persistence service, set this to 0. |
 | rebuildTableNames         | false                                                        |    No     | rename existing tables using `tableUseRealItemNames` and `tableIdDigitCount`. USE WITH CARE! Deactivate after Renaming is done! |
-| jdbc.maximumPoolSize      | configured per database in package `org.openhab.persistence.jdbc.db.*` |    No     | Some embeded databases can handle only one connection.  See [this link](https://github.com/brettwooldridge/HikariCP/issues/256) for more information |
+| jdbc.maximumPoolSize      | configured per database in package `org.openhab.persistence.jdbc.db.*` |    No     | Some embedded databases can handle only one connection. See [this link](https://github.com/brettwooldridge/HikariCP/issues/256) for more information |
 | jdbc.minimumIdle          | see above                                                    |    No     | see above                                                    |
 | enableLogTime             | `false`                                                      |    No     | timekeeping                                                  |
 
@@ -171,4 +171,3 @@ then
 	}
 end
 ```
-

bundles/org.openhab.persistence.jdbc/src/main/java/org/openhab/persistence/jdbc/internal/JdbcPersistenceService.java

@@ -12,8 +12,6 @@
  */
 package org.openhab.persistence.jdbc.internal;
 
-import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
@@ -156,7 +154,7 @@ public class JdbcPersistenceService extends JdbcMapper implements QueryablePersi
     public Iterable<HistoricItem> query(FilterCriteria filter) {
         if (!checkDBAccessability()) {
             logger.warn("JDBC::query: database not connected, query aborted for item '{}'", filter.getItemName());
-            return Collections.emptyList();
+            return List.of();
         }
 
         // Get the item name from the filter
@@ -168,7 +166,7 @@ public class JdbcPersistenceService extends JdbcMapper implements QueryablePersi
             item = itemRegistry.getItem(itemName);
         } catch (ItemNotFoundException e1) {
             logger.error("JDBC::query: unable to get item for itemName: '{}'. Ignore and give up!", itemName);
-            return Collections.emptyList();
+            return List.of();
         }
 
         if (item instanceof GroupItem) {
@@ -177,11 +175,11 @@ public class JdbcPersistenceService extends JdbcMapper implements QueryablePersi
             logger.debug("JDBC::query: item is instanceof GroupItem '{}'", itemName);
             if (item == null) {
                 logger.debug("JDBC::query: BaseItem of GroupItem is null. Ignore and give up!");
-                return Collections.emptyList();
+                return List.of();
             }
             if (item instanceof GroupItem) {
                 logger.debug("JDBC::query: BaseItem of GroupItem is a GroupItem too. Ignore and give up!");
-                return Collections.emptyList();
+                return List.of();
             }
         }
 
@@ -196,8 +194,7 @@ public class JdbcPersistenceService extends JdbcMapper implements QueryablePersi
         }
 
         long timerStart = System.currentTimeMillis();
-        List<HistoricItem> items = new ArrayList<>();
+        List<HistoricItem> items = getHistItemFilterQuery(filter, conf.getNumberDecimalcount(), table, item);
-        items = getHistItemFilterQuery(filter, conf.getNumberDecimalcount(), table, item);
 
         logger.debug("JDBC::query: query for {} returned {} rows in {} ms", item.getName(), items.size(),
                 System.currentTimeMillis() - timerStart);
@@ -224,6 +221,6 @@ public class JdbcPersistenceService extends JdbcMapper implements QueryablePersi
 
     @Override
     public List<PersistenceStrategy> getDefaultStrategies() {
-        return Collections.emptyList();
+        return List.of(PersistenceStrategy.Globals.CHANGE);
     }
 }

bundles/org.openhab.persistence.jdbc/src/main/java/org/openhab/persistence/jdbc/model/JdbcHistoricItem.java

@@ -14,6 +14,7 @@ package org.openhab.persistence.jdbc.model;
 
 import java.time.ZonedDateTime;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.persistence.HistoricItem;
 import org.openhab.core.types.State;
 
@@ -22,6 +23,7 @@ import org.openhab.core.types.State;
  *
  * @author Helmut Lehmeyer - Initial contribution
  */
+@NonNullByDefault
 public class JdbcHistoricItem implements HistoricItem {
 
     private final String name;