diff --git a/libraries/src/main/java/com/baeldung/retrofit/basic/GitHubBasicApp.java b/libraries/src/main/java/com/baeldung/retrofit/basic/GitHubBasicApp.java
index 54a130a67e..6b2cd14252 100644
--- a/libraries/src/main/java/com/baeldung/retrofit/basic/GitHubBasicApp.java
+++ b/libraries/src/main/java/com/baeldung/retrofit/basic/GitHubBasicApp.java
@@ -4,11 +4,11 @@ import java.io.IOException;
 import java.util.List;
 
 public class GitHubBasicApp {
-    
+
     public static void main(String[] args) throws IOException {
         String userName = "eugenp";
-        List<String> topContributors = new GitHubBasicService().getTopContributors(userName);
-        topContributors.stream().forEach(System.out::println);
+        List<String> topContributors = new GitHubBasicService()
+          .getTopContributors(userName);
+        topContributors.forEach(System.out::println);
     }
-
 }
diff --git a/libraries/src/main/java/com/baeldung/retrofit/basic/GitHubBasicService.java b/libraries/src/main/java/com/baeldung/retrofit/basic/GitHubBasicService.java
index fbfdd96567..20256fb540 100644
--- a/libraries/src/main/java/com/baeldung/retrofit/basic/GitHubBasicService.java
+++ b/libraries/src/main/java/com/baeldung/retrofit/basic/GitHubBasicService.java
@@ -1,54 +1,60 @@
 package com.baeldung.retrofit.basic;
 
-import java.io.IOException;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.stream.Collectors;
-
 import com.baeldung.retrofit.models.Contributor;
 import com.baeldung.retrofit.models.Repository;
-
 import retrofit2.Retrofit;
 import retrofit2.converter.gson.GsonConverterFactory;
 
-public class GitHubBasicService {
-    
+import java.io.IOException;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+class GitHubBasicService {
+
     private GitHubBasicApi gitHubApi;
-    
-    public GitHubBasicService() {
+
+    GitHubBasicService() {
         Retrofit retrofit = new Retrofit.Builder()
-            .baseUrl("https://api.github.com/")
-            .addConverterFactory(GsonConverterFactory.create())
-            .build();
-          
-          gitHubApi = retrofit.create(GitHubBasicApi.class);
+          .baseUrl("https://api.github.com/")
+          .addConverterFactory(GsonConverterFactory.create())
+          .build();
+
+        gitHubApi = retrofit.create(GitHubBasicApi.class);
     }
-    
-    public List<String> getTopContributors(String userName) throws IOException {
+
+    List<String> getTopContributors(String userName) throws IOException {
         List<Repository> repos = gitHubApi
           .listRepos(userName)
           .execute()
           .body();
-        
-        List<Contributor> topContributors = new ArrayList<>();
-        for(Repository repo : repos) {
-            List<Contributor> contributers = gitHubApi
-              .listRepoContributors(userName, repo.getName())
-              .execute()
-              .body();
-            
-            List<Contributor> repoTopContributors = contributers.stream()
-              .filter(c -> c.getContributions() > 100)
-              .collect(Collectors.toList());
-            topContributors.addAll(repoTopContributors);
-        }
-        
-        Collections.sort(topContributors, (a, b) -> b.getContributions() - a.getContributions());
-        return topContributors.stream()
-          .map(c -> c.getName())
+
+        repos = repos != null ? repos : Collections.emptyList();
+
+        return repos.stream()
+          .flatMap(repo -> getContributors(userName, repo))
+          .sorted((a, b) -> b.getContributions() - a.getContributions())
+          .map(Contributor::getName)
           .distinct()
+          .sorted()
           .collect(Collectors.toList());
     }
 
+    private Stream<Contributor> getContributors(String userName, Repository repo) {
+        List<Contributor> contributors = null;
+        try {
+            contributors = gitHubApi
+              .listRepoContributors(userName, repo.getName())
+              .execute()
+              .body();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+        contributors = contributors != null ? contributors : Collections.emptyList();
+
+        return contributors.stream()
+          .filter(c -> c.getContributions() > 100);
+    }
 }
diff --git a/libraries/src/main/java/com/baeldung/retrofit/models/Contributor.java b/libraries/src/main/java/com/baeldung/retrofit/models/Contributor.java
index b7b7869ff6..2f8697f603 100644
--- a/libraries/src/main/java/com/baeldung/retrofit/models/Contributor.java
+++ b/libraries/src/main/java/com/baeldung/retrofit/models/Contributor.java
@@ -2,11 +2,6 @@ package com.baeldung.retrofit.models;
 
 import com.google.gson.annotations.SerializedName;
 
-/**
- * GitHub Contributer
- * @author hany
- *
- */
 public class Contributor {
     
     @SerializedName("login")
diff --git a/libraries/src/main/java/com/baeldung/retrofit/models/Repository.java b/libraries/src/main/java/com/baeldung/retrofit/models/Repository.java
index 61e4752ce7..f12fcdf8f2 100644
--- a/libraries/src/main/java/com/baeldung/retrofit/models/Repository.java
+++ b/libraries/src/main/java/com/baeldung/retrofit/models/Repository.java
@@ -1,10 +1,5 @@
 package com.baeldung.retrofit.models;
 
-/**
- * GitHub Repository
- * @author hany
- *
- */
 public class Repository {
     
     private String name;
diff --git a/libraries/src/main/java/com/baeldung/retrofit/rx/GitHubRxApp.java b/libraries/src/main/java/com/baeldung/retrofit/rx/GitHubRxApp.java
index 0e0d8b1a77..b136a1e40b 100644
--- a/libraries/src/main/java/com/baeldung/retrofit/rx/GitHubRxApp.java
+++ b/libraries/src/main/java/com/baeldung/retrofit/rx/GitHubRxApp.java
@@ -3,11 +3,10 @@ package com.baeldung.retrofit.rx;
 import java.io.IOException;
 
 public class GitHubRxApp {
-    
+
     public static void main(String[] args) throws IOException {
         String userName = "eugenp";
         new GitHubRxService().getTopContributors(userName)
           .subscribe(System.out::println);
     }
-    
 }
diff --git a/libraries/src/main/java/com/baeldung/retrofit/rx/GitHubRxService.java b/libraries/src/main/java/com/baeldung/retrofit/rx/GitHubRxService.java
index 56d149d13e..2ad50a9f39 100644
--- a/libraries/src/main/java/com/baeldung/retrofit/rx/GitHubRxService.java
+++ b/libraries/src/main/java/com/baeldung/retrofit/rx/GitHubRxService.java
@@ -1,33 +1,33 @@
 package com.baeldung.retrofit.rx;
 
+import com.baeldung.retrofit.models.Contributor;
 import retrofit2.Retrofit;
 import retrofit2.adapter.rxjava.RxJavaCallAdapterFactory;
 import retrofit2.converter.gson.GsonConverterFactory;
 import rx.Observable;
 
-public class GitHubRxService {
-    
+class GitHubRxService {
+
     private GitHubRxApi gitHubApi;
-    
-    public GitHubRxService() {
+
+    GitHubRxService() {
         Retrofit retrofit = new Retrofit.Builder()
-            .baseUrl("https://api.github.com/")
-            .addConverterFactory(GsonConverterFactory.create())
-            .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
-            .build();
-        
+          .baseUrl("https://api.github.com/")
+          .addConverterFactory(GsonConverterFactory.create())
+          .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
+          .build();
+
         gitHubApi = retrofit.create(GitHubRxApi.class);
     }
-    
-    public Observable<String> getTopContributors(String userName) {
+
+    Observable<String> getTopContributors(String userName) {
         return gitHubApi.listRepos(userName)
-          .flatMap( repos -> Observable.from(repos))
-          .flatMap( repo -> gitHubApi.listRepoContributors(userName, repo.getName()) )
-          .flatMap( contributers -> Observable.from(contributers))
-          .filter( c -> c.getContributions() > 100)
-          .sorted( (a, b) -> b.getContributions() - a.getContributions() )
-          .map( c -> c.getName())
+          .flatMapIterable(x -> x)
+          .flatMap(repo -> gitHubApi.listRepoContributors(userName, repo.getName()))
+          .flatMapIterable(x -> x)
+          .filter(c -> c.getContributions() > 100)
+          .sorted((a, b) -> b.getContributions() - a.getContributions())
+          .map(Contributor::getName)
           .distinct();
     }
-
 }