Fix return type in model setters.

Previously return type was same, as method arguments. It`s wrong, and cause errors like
"Return value of Foo::setSuccess() must be of the type bool, object returned"
We cant use self and current {{classname}} as return type, because that can break class inheritance. So, better remove type hint on setters, until PHP-devs dont make realization for return static

modules/openapi-generator/src/main/resources/php-symfony/model_generic.mustache

@@ -35,7 +35,7 @@ class {{classname}} {{#parentSchema}}extends {{{parent}}} {{/parentSchema}}
      *
      * @return $this
      */
-    public function {{setter}}({{#vendorExtensions.x-parameter-type}}{{vendorExtensions.x-parameter-type}} {{/vendorExtensions.x-parameter-type}}${{name}}{{^required}} = null{{/required}}){{#vendorExtensions.x-parameter-type}}: {{^required}}?{{/required}}{{vendorExtensions.x-parameter-type}}{{/vendorExtensions.x-parameter-type}}
+    public function {{setter}}({{#vendorExtensions.x-parameter-type}}{{vendorExtensions.x-parameter-type}} {{/vendorExtensions.x-parameter-type}}${{name}}{{^required}} = null{{/required}})
     {
         $this->{{name}} = ${{name}};
 

samples/server/petstore/php-symfony/SymfonyBundle-php/Model/Order.php

@@ -197,7 +197,7 @@ public function getShipDate(): ?\DateTime
      *
      * @return $this
      */
-    public function setShipDate(\DateTime $shipDate = null): ?\DateTime
+    public function setShipDate(\DateTime $shipDate = null)
     {
         $this->shipDate = $shipDate;
 

samples/server/petstore/php-symfony/SymfonyBundle-php/Model/Pet.php

@@ -155,7 +155,7 @@ public function getCategory(): ?Category
      *
      * @return $this
      */
-    public function setCategory(Category $category = null): ?Category
+    public function setCategory(Category $category = null)
     {
         $this->category = $category;
 
@@ -203,7 +203,7 @@ public function getPhotoUrls(): array
      *
      * @return $this
      */
-    public function setPhotoUrls(array $photoUrls): array
+    public function setPhotoUrls(array $photoUrls)
     {
         $this->photoUrls = $photoUrls;
 
@@ -227,7 +227,7 @@ public function getTags(): ?array
      *
      * @return $this
      */
-    public function setTags(array $tags = null): ?array
+    public function setTags(array $tags = null)
     {
         $this->tags = $tags;