tim-connector: Add protected default constructor for Hibernate to new entities

Include proper comments warning about not using it directly.

FEA: ItEr77S16JiraAndTimConnectorContributionIntegration

libreplan-business/src/main/java/org/libreplan/business/common/entities/AppProperties.java

@@ -37,6 +37,12 @@ public class AppProperties extends BaseEntity {
     private String propertyName;
     private String propertyValue;
 
+    /**
+     * Constructor for Hibernate. Do not use!
+     */
+    protected AppProperties() {
+    }
+
     public String getMajorId() {
         return majorId;
     }

libreplan-business/src/main/java/org/libreplan/business/common/entities/JobSchedulerConfiguration.java

@@ -32,6 +32,12 @@ public class JobSchedulerConfiguration extends BaseEntity {
         return create(new JobSchedulerConfiguration());
     }
 
+    /**
+     * Constructor for Hibernate. Do not use!
+     */
+    protected JobSchedulerConfiguration() {
+    }
+
     private String jobGroup;
     private String jobName;
     private String triggerGroup;

libreplan-business/src/main/java/org/libreplan/business/orders/entities/OrderSyncInfo.java

@@ -41,8 +41,10 @@ public class OrderSyncInfo extends BaseEntity {
         return create(new OrderSyncInfo(order));
     }
 
+    /**
+     * Constructor for Hibernate. Do not use!
+     */
     protected OrderSyncInfo() {
-
     }
 
     private OrderSyncInfo(Order order) {