MID-8842 ninja - task policy rule processor description added

(cherry picked from commit 8ce402a)

infra/schema/src/main/java/com/evolveum/midpoint/schema/validator/UpgradeObjectProcessor.java

@@ -15,7 +15,7 @@
 public interface UpgradeObjectProcessor<T extends Objectable> extends ProcessorMixin {
 
     /**
-     * @return Unique identifier of the processor. By default it is class name without "Processor" suffix.
+     * @return Unique identifier of the processor. By default, it is class name without "Processor" suffix.
      */
     default String getIdentifier() {
         return getIdentifier(getClass());
@@ -43,6 +43,7 @@ default String getIdentifier() {
      * @param path
      * @return Returns description of the upgrade if not done automatically.
      * Should be single line (might end up in CSV) without any special characters.
+     * Certainly not semicolon (;) and double quote (").
      * Best approach is to put in short description and link to documentation.
      */
     default String upgradeDescription(PrismObject<T> object, ItemPath path) {

infra/schema/src/main/java/com/evolveum/midpoint/schema/validator/processor/TaskPolicyProcessor.java

@@ -38,6 +38,12 @@ public boolean isApplicable(PrismObject<?> object, ItemPath path) {
         return matchParentTypeAndItemName(object, path, TaskType.class, TaskType.F_POLICY_RULE);
     }
 
+    @Override
+    public String upgradeDescription(PrismObject<TaskType> object, ItemPath path) {
+        return "There is a migration to the use of focusValidityScan.validityConstraint item, although not a complete one: "
+                + "even if the ability to recompute objects is retained, custom policy actions can no longer be defined.";
+    }
+
     @Override
     public boolean process(PrismObject<TaskType> object, ItemPath path) throws Exception {
         return false;