diff --git a/modules/swagger-codegen/src/main/resources/Java/ApiClient.mustache b/modules/swagger-codegen/src/main/resources/Java/ApiClient.mustache
index c4e2538b4c3..5d434c6980b 100644
--- a/modules/swagger-codegen/src/main/resources/Java/ApiClient.mustache
+++ b/modules/swagger-codegen/src/main/resources/Java/ApiClient.mustache
@@ -497,9 +497,16 @@ public class ApiClient {
     if (contentType.startsWith("multipart/form-data")) {
       FormDataMultiPart mp = new FormDataMultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof File) {
+        if( param.getValue() instanceof List && !( ( List ) param.getValue() ).isEmpty()
+                  && ( ( List ) param.getValue() ).get( 0 ) instanceof File ) {
+            @SuppressWarnings( "unchecked" )
+            List<File> files = ( List<File> ) param.getValue();
+            for( File file : files ) {
+              mp.bodyPart( new FileDataBodyPart( param.getKey(), file, MediaType.APPLICATION_OCTET_STREAM_TYPE ) );
+            }
+        } else if (param.getValue() instanceof File) {
           File file = (File) param.getValue();
-          mp.bodyPart(new FileDataBodyPart(param.getKey(), file, MediaType.MULTIPART_FORM_DATA_TYPE));
+          mp.bodyPart(new FileDataBodyPart(param.getKey(), file, MediaType.APPLICATION_OCTET_STREAM_TYPE));
         } else {
           mp.field(param.getKey(), parameterToString(param.getValue()), MediaType.MULTIPART_FORM_DATA_TYPE);
         }
diff --git a/samples/client/petstore/java/jersey1/src/main/java/io/swagger/client/ApiClient.java b/samples/client/petstore/java/jersey1/src/main/java/io/swagger/client/ApiClient.java
index b16fdbbdfa9..c3d9ef3457a 100644
--- a/samples/client/petstore/java/jersey1/src/main/java/io/swagger/client/ApiClient.java
+++ b/samples/client/petstore/java/jersey1/src/main/java/io/swagger/client/ApiClient.java
@@ -509,9 +509,16 @@ public class ApiClient {
     if (contentType.startsWith("multipart/form-data")) {
       FormDataMultiPart mp = new FormDataMultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof File) {
+        if( param.getValue() instanceof List && !( ( List ) param.getValue() ).isEmpty()
+                  && ( ( List ) param.getValue() ).get( 0 ) instanceof File ) {
+            @SuppressWarnings( "unchecked" )
+            List<File> files = ( List<File> ) param.getValue();
+            for( File file : files ) {
+              mp.bodyPart( new FileDataBodyPart( param.getKey(), file, MediaType.APPLICATION_OCTET_STREAM_TYPE ) );
+            }
+        } else if (param.getValue() instanceof File) {
           File file = (File) param.getValue();
-          mp.bodyPart(new FileDataBodyPart(param.getKey(), file, MediaType.MULTIPART_FORM_DATA_TYPE));
+          mp.bodyPart(new FileDataBodyPart(param.getKey(), file, MediaType.APPLICATION_OCTET_STREAM_TYPE));
         } else {
           mp.field(param.getKey(), parameterToString(param.getValue()), MediaType.MULTIPART_FORM_DATA_TYPE);
         }