[1007] Improve direct edit on Feature with ":=" and "default" symbols

Bug: #1007
Signed-off-by: Arthur Daussy <arthur.daussy@obeo.fr>

Author: adaussy

CHANGELOG.adoc

@@ -14,7 +14,8 @@
 
 === Improvements
 
--https://github.com/eclipse-syson/syson/issues/1061[#1061] [general-view] Add ellipsis on `Packages` label, to provide visual feedback on name overflow.
+- https://github.com/eclipse-syson/syson/issues/1061[#1061] [general-view] Add ellipsis on `Packages` label, to provide visual feedback on name overflow.
+- https://github.com/eclipse-syson/syson/issues/1007[#1007] Improve direct edit on Feature elements to be able to set the `isDefault` and `isInitial` properties
 
 === New features
 

backend/application/syson-sysml-export/src/main/java/org/eclipse/syson/sysml/export/SysMLElementSerializer.java

@@ -1210,7 +1210,7 @@ private void appendValuePart(Appender builder, Usage usage) {
                 builder.appendWithSpaceIfNeeded(LabelConstants.DEFAULT);
             }
             if (feature.isIsInitial()) {
-                builder.appendWithSpaceIfNeeded(":=");
+                builder.appendWithSpaceIfNeeded(LabelConstants.COLON_EQUAL);
             } else {
                 builder.appendWithSpaceIfNeeded(LabelConstants.EQUAL);
             }

backend/metamodel/syson-sysml-metamodel/src/main/java/org/eclipse/syson/sysml/helper/LabelConstants.java

@@ -41,6 +41,8 @@ public class LabelConstants {
 
     public static final String EQUAL = "=";
 
+    public static final String COLON_EQUAL = ":=";
+
     public static final String GREATER_THAN = ">";
 
     public static final String IN = "in";