diff --git a/modules/swagger-codegen/src/main/resources/Java/auth/HttpBasicAuth.mustache b/modules/swagger-codegen/src/main/resources/Java/auth/HttpBasicAuth.mustache
index 28d5703b75..22a64b1a24 100644
--- a/modules/swagger-codegen/src/main/resources/Java/auth/HttpBasicAuth.mustache
+++ b/modules/swagger-codegen/src/main/resources/Java/auth/HttpBasicAuth.mustache
@@ -27,8 +27,9 @@ public class HttpBasicAuth implements Authentication {
 
   @Override
   public void applyToParams(Map<String, String> queryParams, Map<String, String> headerParams) {
+    String str = (username == null ? "" : username) + ":" + (password == null ? "" : password);
     try {
-      headerParams.put("Authorization", "Basic " + DatatypeConverter.printBase64Binary((username + ":" + password).getBytes("UTF-8")));
+      headerParams.put("Authorization", "Basic " + DatatypeConverter.printBase64Binary(str.getBytes("UTF-8")));
     } catch (UnsupportedEncodingException e) {
       throw new RuntimeException(e);
     }
diff --git a/samples/client/petstore/java/src/main/java/io/swagger/client/auth/HttpBasicAuth.java b/samples/client/petstore/java/src/main/java/io/swagger/client/auth/HttpBasicAuth.java
index 37ceffa163..24bff8c226 100644
--- a/samples/client/petstore/java/src/main/java/io/swagger/client/auth/HttpBasicAuth.java
+++ b/samples/client/petstore/java/src/main/java/io/swagger/client/auth/HttpBasicAuth.java
@@ -27,8 +27,9 @@ public class HttpBasicAuth implements Authentication {
 
   @Override
   public void applyToParams(Map<String, String> queryParams, Map<String, String> headerParams) {
+    String str = (username == null ? "" : username) + ":" + (password == null ? "" : password);
     try {
-      headerParams.put("Authorization", "Basic " + DatatypeConverter.printBase64Binary((username + ":" + password).getBytes("UTF-8")));
+      headerParams.put("Authorization", "Basic " + DatatypeConverter.printBase64Binary(str.getBytes("UTF-8")));
     } catch (UnsupportedEncodingException e) {
       throw new RuntimeException(e);
     }
diff --git a/samples/client/petstore/java/src/test/java/io/swagger/client/auth/HttpBasicAuthTest.java b/samples/client/petstore/java/src/test/java/io/swagger/client/auth/HttpBasicAuthTest.java
index dc57a61391..87d6eca8b8 100644
--- a/samples/client/petstore/java/src/test/java/io/swagger/client/auth/HttpBasicAuthTest.java
+++ b/samples/client/petstore/java/src/test/java/io/swagger/client/auth/HttpBasicAuthTest.java
@@ -27,7 +27,22 @@ public class HttpBasicAuthTest {
     assertEquals(0, queryParams.size());
     assertEquals(1, headerParams.size());
     // the string below is base64-encoded result of "my-username:my-password" with the "Basic " prefix
-    final String expected = "Basic bXktdXNlcm5hbWU6bXktcGFzc3dvcmQ=";
+    String expected = "Basic bXktdXNlcm5hbWU6bXktcGFzc3dvcmQ=";
+    assertEquals(expected, headerParams.get("Authorization"));
+
+    // null username should be treated as empty string
+    auth.setUsername(null);
+    auth.applyToParams(queryParams, headerParams);
+    // the string below is base64-encoded result of ":my-password" with the "Basic " prefix
+    expected = "Basic Om15LXBhc3N3b3Jk";
+    assertEquals(expected, headerParams.get("Authorization"));
+
+    // null password should be treated as empty string
+    auth.setUsername("my-username");
+    auth.setPassword(null);
+    auth.applyToParams(queryParams, headerParams);
+    // the string below is base64-encoded result of "my-username:" with the "Basic " prefix
+    expected = "Basic bXktdXNlcm5hbWU6";
     assertEquals(expected, headerParams.get("Authorization"));
   }
 }