diff --git a/stream/src/main/java/org/apache/kafka/streaming/processor/internals/ProcessorNode.java b/stream/src/main/java/org/apache/kafka/streaming/processor/internals/ProcessorNode.java
index fa1dbb1e734bc..feee522158011 100644
--- a/stream/src/main/java/org/apache/kafka/streaming/processor/internals/ProcessorNode.java
+++ b/stream/src/main/java/org/apache/kafka/streaming/processor/internals/ProcessorNode.java
@@ -40,15 +40,15 @@ public ProcessorNode(String name, Processor<K, V> processor) {
         this.children = new ArrayList<>();
     }
 
-    public String name() {
+    public final String name() {
         return name;
     }
 
-    public List<ProcessorNode<?, ?>> children() {
+    public final List<ProcessorNode<?, ?>> children() {
         return children;
     }
 
-    public final void addChild(ProcessorNode<?, ?> child) {
+    public void addChild(ProcessorNode<?, ?> child) {
         children.add(child);
     }
 
diff --git a/stream/src/main/java/org/apache/kafka/streaming/processor/internals/SinkNode.java b/stream/src/main/java/org/apache/kafka/streaming/processor/internals/SinkNode.java
index 14bec7ea5fc65..93e8724dee8fd 100644
--- a/stream/src/main/java/org/apache/kafka/streaming/processor/internals/SinkNode.java
+++ b/stream/src/main/java/org/apache/kafka/streaming/processor/internals/SinkNode.java
@@ -40,6 +40,11 @@ public SinkNode(String name, String topic, Serializer<K> keySerializer, Serializ
         this.valSerializer = valSerializer;
     }
 
+    @Override
+    public void addChild(ProcessorNode<?, ?> child) {
+        throw new UnsupportedOperationException("sink node does not allow addChild");
+    }
+
     @Override
     public void init(ProcessorContext context) {
         this.context = context;