Add ability to compute specific item modification count

1. Counts modifications based on the specified item path.

docs/simulation/results/metrics.adoc

@@ -436,3 +436,36 @@ We can restrict the selection (or domain) of the original metric to cover only s
 ----
 <1> The `after` item represents the object state after the operation.
 (Note that if the `department` attribute itself is modified to a value other than "Security services", this change is not seen by this simple filter.)
+
+Let's explore how to configure the system to determine whether any changes have occurred to
+a specific attribute such as `employeeNumber`.
+
+.Listing 7. Computation of attribute modifications for specific item path
+[source,xml]
+----
+<metric>
+    <identifier>attribute-modifications-employee-number</identifier>
+    <computation>
+        <domain>
+            <expression>
+                <script>
+                    <code>processedObject.isShadow()</code>
+                </script>
+            </expression>
+        </domain>
+        <valueExpression>
+            <script>
+                <code>
+                    import com.evolveum.midpoint.prism.path.ItemPath;
+                    def itemPath = ItemPath.create('attributes','employeeNumber');<!--1-->
+
+                    return processedObject.getItemModificationsCount(itemPath);<!--2-->
+                </code>
+            </script>
+        </valueExpression>
+    </computation>
+</metric>
+----
+<1> Define the item path for 'employeeNumber'. The item path must exactly match the configuration.
+<2> Compute the count of modifications for the specified item path.
+To include sub-item modifications, use `getItemModificationsCount(itemPath, true)`.

model/model-impl/src/main/java/com/evolveum/midpoint/model/impl/simulation/ProcessedObjectImpl.java

@@ -682,6 +682,48 @@ private boolean isAttributeModification(@NotNull ItemDelta<?, ?> modification) {
         return ShadowType.F_ATTRIBUTES.equivalent(modification.getParentPath());
     }
 
+    /**
+     * Counts modifications based on the specified path, excluding changes in ADD/DELETE deltas.
+     * <p>
+     * The item path must exactly match the configuration.
+     * </p>
+     * Sub-item modifications are not counted.
+     *
+     * @param itemPath the path to count modifications for
+     * @return the number of attribute modifications.
+     */
+    @SuppressWarnings("unused") // used in scripts
+    public int getItemModificationsCount(@NotNull ItemPath itemPath) {
+        return getItemModificationsCount(itemPath, false);
+    }
+
+    /**
+     * Counts modifications based on the specified path, excluding changes in ADD/DELETE deltas.
+     * <p>
+     * The item path must exactly match the configuration.
+     * </p>
+     * If {@code allowSubPaths} is true, sub-item modifications are also counted.
+     *
+     * @param itemPath the path to count modifications for
+     * @param allowSubPaths if true, sub-item modifications are allowed
+     * @return the number of attribute modifications
+     */
+    @SuppressWarnings("unused") // used in scripts
+    public int getItemModificationsCount(@NotNull ItemPath itemPath, boolean allowSubPaths) {
+        if (delta == null || !delta.isModify()) {
+            return 0;
+        }
+
+        return (int) delta.getModifications().stream()
+                .filter(itemDelta -> {
+                    ItemPath deltaPath = itemDelta.getPath();
+                    return allowSubPaths
+                            ? deltaPath.isSuperPathOrEquivalent(itemPath)
+                            : deltaPath.equivalent(itemPath);
+                })
+                .count();
+    }
+
     /**
      * Returns the number of VALUES of associations added or deleted.
      *