diff --git a/modules/swagger-codegen/src/main/resources/php/api.mustache b/modules/swagger-codegen/src/main/resources/php/api.mustache
index 74c32a891f3..bf059063ffd 100644
--- a/modules/swagger-codegen/src/main/resources/php/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/php/api.mustache
@@ -44,8 +44,12 @@ class {{classname}} {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = '{{#produces}}{{mediaType}}{{#hasMore}},{{/hasMore}}{{/produces}}';
-      $headerParams['Content-Type'] = '{{#consumes}}{{mediaType}}{{#hasMore}},{{/hasMore}}{{/consumes}}';
+      $_header_accept = '{{#produces}}{{mediaType}}{{#hasMore}}, {{/hasMore}}{{/produces}}';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array({{#consumes}}'{{mediaType}}'{{#hasMore}},{{/hasMore}}{{/consumes}});
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       {{#queryParams}}// query params
       if(${{paramName}} !== null) {
diff --git a/samples/client/petstore/php/PetApi.php b/samples/client/petstore/php/PetApi.php
index 87850e3128d..a972a5c995b 100644
--- a/samples/client/petstore/php/PetApi.php
+++ b/samples/client/petstore/php/PetApi.php
@@ -43,8 +43,12 @@ class PetApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = 'application/json,application/xml';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array('application/json','application/xml');
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
@@ -88,8 +92,12 @@ class PetApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = 'application/json,application/xml';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array('application/json','application/xml');
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
@@ -133,8 +141,12 @@ class PetApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       // query params
       if($status !== null) {
@@ -183,8 +195,12 @@ class PetApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       // query params
       if($tags !== null) {
@@ -233,8 +249,12 @@ class PetApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
@@ -286,8 +306,12 @@ class PetApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = 'application/x-www-form-urlencoded';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array('application/x-www-form-urlencoded');
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
@@ -338,8 +362,12 @@ class PetApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       // header params
@@ -388,8 +416,12 @@ class PetApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = 'multipart/form-data';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array('multipart/form-data');
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
diff --git a/samples/client/petstore/php/StoreApi.php b/samples/client/petstore/php/StoreApi.php
index 6ff2f83d1be..169766a8e76 100644
--- a/samples/client/petstore/php/StoreApi.php
+++ b/samples/client/petstore/php/StoreApi.php
@@ -42,8 +42,12 @@ class StoreApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
@@ -89,8 +93,12 @@ class StoreApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
@@ -140,8 +148,12 @@ class StoreApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
@@ -191,8 +203,12 @@ class StoreApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
diff --git a/samples/client/petstore/php/UserApi.php b/samples/client/petstore/php/UserApi.php
index a811d8c9f97..4d5c3de954f 100644
--- a/samples/client/petstore/php/UserApi.php
+++ b/samples/client/petstore/php/UserApi.php
@@ -43,8 +43,12 @@ class UserApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
@@ -88,8 +92,12 @@ class UserApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
@@ -133,8 +141,12 @@ class UserApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
@@ -179,8 +191,12 @@ class UserApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       // query params
       if($username !== null) {
@@ -231,8 +247,12 @@ class UserApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
@@ -272,8 +292,12 @@ class UserApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
@@ -324,8 +348,12 @@ class UserApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';
 
       
       
@@ -373,8 +401,12 @@ class UserApi {
       $queryParams = array();
       $headerParams = array();
       $formParams = array();
-      $headerParams['Accept'] = 'application/json,application/xml';
-      $headerParams['Content-Type'] = '';
+      $_header_accept = 'application/json, application/xml';
+      if ($_header_accept !== '') {
+        $headerParams['Accept'] = $_header_accept;
+      }
+      $_header_content_type = array();
+      $headerParams['Content-Type'] = count($_header_content_type) > 0 ? $_header_content_type[0] : 'application/json';