diff --git a/callback/src/main/java/com/iluwatar/callback/App.java b/callback/src/main/java/com/iluwatar/callback/App.java
index 546a6b507..513a32415 100644
--- a/callback/src/main/java/com/iluwatar/callback/App.java
+++ b/callback/src/main/java/com/iluwatar/callback/App.java
@@ -1,8 +1,10 @@
 package com.iluwatar.callback;
 
 /**
- * Callback pattern is more native for functional languages where function is treated as first-class citizen.
- * Prior to Java8 can be simulated using simple (alike command) interfaces.
+ * 
+ * Callback pattern is more native for functional languages where functions are treated as first-class citizens.
+ * Prior to Java 8 callbacks can be simulated using simple (alike command) interfaces.
+ * 
  */
 public class App {
 
diff --git a/callback/src/main/java/com/iluwatar/callback/Callback.java b/callback/src/main/java/com/iluwatar/callback/Callback.java
index 9e757e218..81a421c0d 100644
--- a/callback/src/main/java/com/iluwatar/callback/Callback.java
+++ b/callback/src/main/java/com/iluwatar/callback/Callback.java
@@ -1,7 +1,9 @@
 package com.iluwatar.callback;
 
 /**
+ * 
  * Callback interface
+ * 
  */
 public interface Callback {
 
diff --git a/callback/src/main/java/com/iluwatar/callback/SimpleTask.java b/callback/src/main/java/com/iluwatar/callback/SimpleTask.java
index f8a27ba10..58f35709f 100644
--- a/callback/src/main/java/com/iluwatar/callback/SimpleTask.java
+++ b/callback/src/main/java/com/iluwatar/callback/SimpleTask.java
@@ -1,7 +1,9 @@
 package com.iluwatar.callback;
 
 /**
+ * 
  * Implementation of task that need to be executed
+ * 
  */
 public class SimpleTask extends Task {
 
diff --git a/callback/src/main/java/com/iluwatar/callback/Task.java b/callback/src/main/java/com/iluwatar/callback/Task.java
index df7bf8ae8..db4b66dc5 100644
--- a/callback/src/main/java/com/iluwatar/callback/Task.java
+++ b/callback/src/main/java/com/iluwatar/callback/Task.java
@@ -1,7 +1,9 @@
 package com.iluwatar.callback;
 
 /**
+ * 
  * Template-method class for callback hook execution
+ * 
  */
 public abstract class Task {
 
diff --git a/callback/src/test/java/com/iluwatar/callback/AppTest.java b/callback/src/test/java/com/iluwatar/callback/AppTest.java
index 5d7febcee..aceac1c62 100644
--- a/callback/src/test/java/com/iluwatar/callback/AppTest.java
+++ b/callback/src/test/java/com/iluwatar/callback/AppTest.java
@@ -4,6 +4,11 @@ import org.junit.Test;
 
 import com.iluwatar.callback.App;
 
+/**
+ * 
+ * Application test
+ *
+ */
 public class AppTest {
 
 	@Test