image-processing: Divide adapter example into multiple classes

image-processing/index.md

@@ -109,19 +109,25 @@ public class ExampleGraph implements Graph<Node> {
         return node.neighbors();
     }
 }
+```
 
+```java
 public class Source implements Node {
     public List<Node> neighbors() {
         ...
     }
 }
+```
 
+```java
 public class Sink implements Node {
     public List<Node> neighbors() {
         ...
     }
 }
+```
 
+```java
 public class Pixel implements Node {
     public List<Node> neighbors() {
         ...