feat: Implement visit for mapping property nary in pipeline element t…

…emplates (#3029)

streampipes-pipeline-management/src/main/java/org/apache/streampipes/manager/template/PipelineElementTemplateVisitor.java

@@ -105,7 +105,10 @@ public void visit(FreeTextStaticProperty freeTextStaticProperty) {
 
   @Override
   public void visit(MappingPropertyNary mappingPropertyNary) {
-    // Do nothing, not supported by pipeline element templates
+    if (hasKey(mappingPropertyNary)) {
+      var selectedProperties = getValueAsList(mappingPropertyNary);
+      mappingPropertyNary.setSelectedProperties(selectedProperties);
+    }
   }
 
   @Override

streampipes-pipeline-management/src/test/java/org/apache/streampipes/manager/template/PipelineElementTemplateVisitorTest.java

@@ -0,0 +1,75 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package org.apache.streampipes.manager.template;
+
+import org.apache.streampipes.model.staticproperty.MappingPropertyNary;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import static org.mockito.ArgumentMatchers.anyList;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+class PipelineElementTemplateVisitorTest {
+  private static final String PROPERTY_NAME = "propertyName";
+
+  private PipelineElementTemplateVisitor visitor;
+  private Map<String, Object> configs;
+  private MappingPropertyNary mappingPropertyNary;
+
+  @BeforeEach
+  void setUp() {
+    configs = new HashMap<>();
+    visitor = new PipelineElementTemplateVisitor(configs);
+    mappingPropertyNary = mock(MappingPropertyNary.class);
+    when(mappingPropertyNary.getInternalName()).thenReturn(PROPERTY_NAME);
+  }
+
+  @Test
+  void visitMappingPropertyNary_SetsSelectedPropertiesWhenKeyExists() {
+    List<String> expectedValues = List.of("value1", "value2");
+    configs.put(PROPERTY_NAME, expectedValues);
+    visitor.visit(mappingPropertyNary);
+
+    verify(mappingPropertyNary).setSelectedProperties(expectedValues);
+  }
+
+  @Test
+  void visitMappingPropertyNary_DoesNothingWhenKeyDoesNotExist() {
+    visitor.visit(mappingPropertyNary);
+
+    verify(mappingPropertyNary, never()).setSelectedProperties(anyList());
+  }
+
+  @Test
+  void visitMappingPropertyNary_HandlesEmptySelectedPropertiesCorrectly() {
+    List<String> expectedValues = List.of();
+    configs.put(PROPERTY_NAME, expectedValues);
+    visitor.visit(mappingPropertyNary);
+
+    verify(mappingPropertyNary).setSelectedProperties(expectedValues);
+  }
+}