[1634] Invalid of export of redefining Attribute with shortName

CHANGELOG.adoc

@@ -58,6 +58,7 @@ Also introduces new `ServiceMethod` helper class to build AQL service call expre
 - https://github.com/eclipse-syson/syson/issues/1621[#1621] [diagrams] Fix an issue where the creation of a _Package_ inside another _Package_ created the _Package_ at the root of the diagram in addition to the inside of the target _Package_.
 - https://github.com/eclipse-syson/syson/issues/1617[#1617] [import] Fix incorrect resolution of _redefined feature_ on `Redefinitions` during textual import.
 - https://github.com/eclipse-syson/syson/issues/1627[#1627] [import] [export] Fix invalid textual import/export of `LiteralRational`.
+- https://github.com/eclipse-syson/syson/issues/1634[#1634] [export] Redefining an `AttributeUsage` with a _shortName_ does not properly export to the textual format.
 
 === Improvements
 

backend/application/syson-application/src/test/java/org/eclipse/syson/application/export/ImportExportTests.java

@@ -888,6 +888,29 @@ public void checkFeatureReferenceExpressionWithQualifiedNameDeresolution() throw
         this.checker.check(input, input);
     }
 
+    @Test
+    @DisplayName("GIVEN a model with an attribute redefining an attribute with a short name, WHEN importing and exporting the model, THEN the redefined attribute should not redefine the shortName")
+    public void checkRedefineAttributeWithShortName() throws IOException {
+        var input = """
+                part p {
+                    attribute <a> anAttribute;
+                }
+
+                part p1 :> p {
+                    attribute :>> a;
+                }""";
+        var expected = """
+                part p {
+                    attribute <a> anAttribute;
+                }
+                part p1 :> p {
+                    attribute :>> anAttribute;
+                }""";
+
+        this.checker.check(input, expected);
+    }
+
+
     @Test
     @DisplayName("GIVEN a model with an AttributeUsage containing a LiteralString, WHEN importing and exporting the model, THEN the exported text file should be the same as the imported one.")
     public void checkLiteralString() throws IOException {

backend/metamodel/syson-sysml-metamodel/src/main/java/org/eclipse/syson/sysml/textual/SysMLElementSerializer.java

@@ -1874,7 +1874,7 @@ private String buildImportContextRelativeQualifiedName(Element element, Element
     }
 
     private String appendNameWithShortName(Appender builder, Element element) {
-        String shortName = element.getShortName();
+        String shortName = element.getDeclaredShortName();
         if (!this.isNullOrEmpty(shortName)) {
             builder.appendSpaceIfNeeded().append("<").appendPrintableName(shortName).append(">");
         }

doc/content/modules/user-manual/pages/release-notes/2025.12.0.adoc

@@ -62,7 +62,8 @@ metadata def MP :> SemanticMetadata {
 }
 ```
 
-- Fix an issue during import and export of rational numbers.
+- Fix an issue during texual import and export of rational numbers.
+
 The following model is now properly imported:
 
 ```
@@ -99,6 +100,41 @@ package Occurrences {
 }
 ```
 
+- Fix an issue where a model with a redefining `AttributeUsage` incorrectly redefined a _short name_ during a textual export.
+For example with the following model:
+
+```
+part p {
+    attribute <a> anAttribute;
+}
+
+part p1 :> p {
+    attribute :>> anAttribute;
+}
+```
+
+The export gave :
+
+```
+part p {
+	attribute <a> anAttribute;
+}
+part p1 :> p {
+	attribute <a> :>> anAttribute;
+}
+```
+
+Instead, it now exports:
+
+```
+part p {
+	attribute <a> anAttribute;
+}
+part p1 :> p {
+	attribute :>> anAttribute;
+}
+```
+
 == Improvements
 
 - In diagrams, when using direct edit on graphical elements, it's now possible to use _short names_ in the qualified names.