[1318] Fix issue with adding values to multi-valued references

CHANGELOG.adoc

@@ -42,6 +42,7 @@ When creating a new `Perform Action` referencing an existing `Action`, all compa
 - https://github.com/eclipse-syson/syson/issues/1324[#1324] [details] Fix an issue that prevents ending up with a `null` reference in the reference widget.
 - https://github.com/eclipse-syson/syson/issues/1090[#1090] [import] Fix the textual import of `MultiplicityRange` with lower and upper bounds.
 The import now correctly creates a `MultiplicityRange` containing `LiteralInteger` elements for integer bounds, and `FeatureReferenceExpression` elements for feature bounds.
+- https://github.com/eclipse-syson/syson/issues/1318[#1318] [details] Fix an issue that prevents adding a new value to a multi-valued reference in the reference widget.
 
 === Improvements
 

backend/application/syson-application-configuration/src/main/java/org/eclipse/syson/application/services/DetailsViewService.java

@@ -126,6 +126,8 @@ public boolean setNewValue(Element element, EStructuralFeature eStructuralFeatur
             }
             if (eStructuralFeature.getEType() instanceof EEnum && eStructuralFeature.isUnsettable() && !(valueToSet instanceof Enumerator)) {
                 element.eUnset(eStructuralFeature);
+            } else if (eStructuralFeature.isMany() && newValue instanceof List<?> newListValue) {
+                ((List<Object>) element.eGet(eStructuralFeature)).addAll(newListValue);
             } else {
                 if (eStructuralFeature.getEType() instanceof EDataType eDataType && newValue instanceof String stringValue) {
                     valueToSet = EcoreUtil.createFromString(eDataType, stringValue);
@@ -185,9 +187,9 @@ public boolean isReadOnly(Element element) {
      * and isReadOnly(EStructuralFeature).
      *
      * @param element
-     *            The {@link Element} to check
+     *         The {@link Element} to check
      * @param eStructuralFeature
-     *            The {@link EStructuralFeature} to check
+     *         The {@link EStructuralFeature} to check
      * @return
      */
     public boolean isReadOnly(Element element, EStructuralFeature eStructuralFeature) {
@@ -227,11 +229,7 @@ public boolean isReadOnlyStringAttribute(Element element, EStructuralFeature eSt
 
     public boolean isMultilineStringAttribute(Element element, EStructuralFeature eStructuralFeature) {
         boolean isMultiline = false;
-        if (this.isBodyField(eStructuralFeature)) {
-            isMultiline = true;
-        } else {
-            isMultiline = false;
-        }
+        isMultiline = this.isBodyField(eStructuralFeature);
         return isMultiline;
     }
 
@@ -343,9 +341,9 @@ public Element handleReferenceWidgetNewValue(Element element, String eStructural
      * feature.
      *
      * @param feature
-     *            the current {@link Feature}.
+     *         the current {@link Feature}.
      * @param newValue
-     *            the newValue to set.
+     *         the newValue to set.
      * @return the real element (i.e. a FeatureTyping) that holds the property to set.
      */
     public Element handleFeatureTypingNewValue(Feature feature, Object newValue) {
@@ -369,7 +367,7 @@ public Element handleFeatureTypingNewValue(Feature feature, Object newValue) {
      * Get the real owner of the reference widget for the extra property "Typed by".
      *
      * @param element
-     *            the current {@link Element}.
+     *         the current {@link Element}.
      * @return the real element that holds the property.
      */
     public Element getFeatureTypingOwnerExpression(Element element) {
@@ -437,7 +435,6 @@ public boolean setTransitionSourceParameter(TransitionUsage transitionUsage, Ele
             // Update transition source
             transitionUsage.getOwnedMembership().stream()
                     .filter(Objects::nonNull)
-                    .map(Membership.class::cast)
                     .findFirst()
                     .ifPresent(mem -> mem.setMemberElement(au));
             // Update succession source
@@ -583,7 +580,7 @@ public Element setNewDocumentationValue(Element self, String newValue) {
      * Returns the element that owns the visibility feature of the given element.
      *
      * @param self
-     *            An element for which the visibility owner is being searched.
+     *         An element for which the visibility owner is being searched.
      * @return the element that owns the visibility feature of the given element
      */
     public Element getVisibilityPropertyOwner(Element self) {
@@ -597,7 +594,7 @@ public Element getVisibilityPropertyOwner(Element self) {
      * Returns the enumeration literals for the visibility feature of the given element.
      *
      * @param self
-     *            An element for which the list of visibility literals are being searched.
+     *         An element for which the list of visibility literals are being searched.
      * @return the enumeration literals for the visibility feature of the given element.
      */
     public List<EEnumLiteral> getVisibilityEnumLiterals(Element self) {
@@ -612,7 +609,7 @@ public List<EEnumLiteral> getVisibilityEnumLiterals(Element self) {
      * Returns the visibility value of the given element.
      *
      * @param self
-     *            An element for which the list of visibility literals are being searched.
+     *         An element for which the list of visibility literals are being searched.
      * @return the current value of the visibility feature of the given element.
      */
     public EEnumLiteral getVisibilityValue(Element self) {
@@ -627,11 +624,11 @@ public EEnumLiteral getVisibilityValue(Element self) {
      * Sets the visibility value of the given element.
      *
      * @param self
-     *            An element for which the list of visibility literals are being searched.
+     *         An element for which the list of visibility literals are being searched.
      * @param newValue
-     *            the value to set.
+     *         the value to set.
      * @return <code>true</code> if the visibility feature of the given element has been properly set and
-     *         <code>false</code> otherwise.
+     * <code>false</code> otherwise.
      */
     public boolean setVisibilityValue(Element self, Object newValue) {
         boolean result = false;
@@ -668,7 +665,7 @@ private void handleImplied(Element element, EStructuralFeature eStructuralFeatur
      * guarantee that it is well formed after its call.
      *
      * @param aau
-     *            an {@link AcceptActionUsage}
+     *         an {@link AcceptActionUsage}
      */
     private void checkAndRepairAcceptActionUsageStructure(AcceptActionUsage aau) {
         this.checkAndRepairAcceptActionUsagePayload(aau);

doc/content/modules/user-manual/pages/release-notes/2025.6.0.adoc

@@ -52,6 +52,7 @@ image::view-usage-nodes.png[ViewUsage nodes, width=65%,height=65%]
 
 image::view-usage-graphical-contents.png[ViewUsage graphical contents, width=65%,height=65%]
 
+- In the _Details_ view, fix an issue that prevents adding a new value to a multi-valued reference on a reference widget.
 
 == Improvements