diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/JSON.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/JSON.java
index df84d97023..15ce43f658 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/JSON.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/JSON.java
@@ -28,6 +28,7 @@ import org.threeten.bp.OffsetDateTime;
 import org.threeten.bp.format.DateTimeFormatter;
 
 import io.swagger.client.model.*;
+import okio.ByteString;
 
 import java.io.IOException;
 import java.io.StringReader;
@@ -46,6 +47,7 @@ public class JSON {
     private SqlDateTypeAdapter sqlDateTypeAdapter = new SqlDateTypeAdapter();
     private OffsetDateTimeTypeAdapter offsetDateTimeTypeAdapter = new OffsetDateTimeTypeAdapter();
     private LocalDateTypeAdapter localDateTypeAdapter = new LocalDateTypeAdapter();
+    private ByteArrayAdapter byteArrayAdapter = new ByteArrayAdapter();
 
     public static GsonBuilder createGson() {
         GsonFireBuilder fireBuilder = new GsonFireBuilder()
@@ -87,6 +89,7 @@ public class JSON {
             .registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter)
             .registerTypeAdapter(OffsetDateTime.class, offsetDateTimeTypeAdapter)
             .registerTypeAdapter(LocalDate.class, localDateTypeAdapter)
+            .registerTypeAdapter(byte[].class, byteArrayAdapter)
             .create();
     }
 
@@ -153,6 +156,34 @@ public class JSON {
         }
     }
 
+    /**
+     * Gson TypeAdapter for Byte Array type
+     */
+    public class ByteArrayAdapter extends TypeAdapter<byte[]> {
+
+        @Override
+        public void write(JsonWriter out, byte[] value) throws IOException {
+            if (value == null) {
+                out.nullValue();
+            } else {
+                out.value(ByteString.of(value).base64());
+            }
+        }
+
+        @Override
+        public byte[] read(JsonReader in) throws IOException {
+            switch (in.peek()) {
+                case NULL:
+                    in.nextNull();
+                    return null;
+                default:
+                    String bytesAsBase64 = in.nextString();
+                    ByteString byteString = ByteString.decodeBase64(bytesAsBase64);
+                    return byteString.toByteArray();
+            }
+        }
+    }
+
     /**
      * Gson TypeAdapter for JSR310 OffsetDateTime type
      */
diff --git a/samples/client/petstore/java/okhttp-gson/.swagger-codegen/VERSION b/samples/client/petstore/java/okhttp-gson/.swagger-codegen/VERSION
index b4308ebebb..855ff9501e 100644
--- a/samples/client/petstore/java/okhttp-gson/.swagger-codegen/VERSION
+++ b/samples/client/petstore/java/okhttp-gson/.swagger-codegen/VERSION
@@ -1 +1 @@
-2.4.0-SNAPSHOT
+2.4.0-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore/java/okhttp-gson/build.gradle b/samples/client/petstore/java/okhttp-gson/build.gradle
index b6f39a58d5..349c0805d9 100644
--- a/samples/client/petstore/java/okhttp-gson/build.gradle
+++ b/samples/client/petstore/java/okhttp-gson/build.gradle
@@ -91,14 +91,6 @@ if(hasProperty('target') && target == 'android') {
        main = System.getProperty('mainClass')
        classpath = sourceSets.main.runtimeClasspath
     }
-
-    compileJava {
-        options.encoding = "UTF8"
-    }
-
-    compileTestJava {
-        options.encoding = "UTF8"
-    }
 }
 
 dependencies {