fix(model-api): add default implementations for backwards compatibility

Author: mhuster23

model-api/src/commonMain/kotlin/org/modelix/model/api/INode.kt

@@ -54,7 +54,9 @@ interface INode {
      * @param concept the concept of the new node
      * @return replacement for this node with the new given concept
      */
-    fun replaceNode(concept: ConceptReference): INode
+    fun replaceNode(concept: ConceptReference): INode {
+        throw UnsupportedOperationException() // Default implementation to avoid breaking change
+    }
 
     /**
      * Role of this node in its parent node if it exists,or null otherwise.

model-api/src/commonMain/kotlin/org/modelix/model/api/ITreeChangeVisitor.kt

@@ -31,7 +31,7 @@ interface ITreeChangeVisitor {
      *
      * @param nodeId id of the affected node
      */
-    fun conceptChanged(nodeId: Long)
+    fun conceptChanged(nodeId: Long) {} // Noop default implementation to avoid breaking change
 
     /**
      * Called when the children of a node have changed.