refactor: add return type-hints to private methods (#1097)

Author: deguif

Grid/Column/Column.php

@@ -370,7 +370,7 @@ public function isFiltered()
     /**
      * @return bool
      */
-    private function hasFromOperandFilter()
+    private function hasFromOperandFilter(): bool
     {
         if (!isset($this->data['from'])) {
             return false;
@@ -386,7 +386,7 @@ private function hasFromOperandFilter()
     /**
      * @return bool
      */
-    private function hasToOperandFilter()
+    private function hasToOperandFilter(): bool
     {
         if (!isset($this->data['to'])) {
             return false;
@@ -402,7 +402,7 @@ private function hasToOperandFilter()
     /**
      * @return bool
      */
-    private function hasOperatorFilter()
+    private function hasOperatorFilter(): bool
     {
         if (!isset($this->data['operator'])) {
             return false;

Grid/GridFactory.php

@@ -121,7 +121,7 @@ private function resolveType($type)
      *
      * @return array
      */
-    private function resolveOptions(GridTypeInterface $type, Source $source = null, array $options = [])
+    private function resolveOptions(GridTypeInterface $type, Source $source = null, array $options = []): array
     {
         $resolver = new OptionsResolver();