Match selection dialog box shadow with barrier color

lib/country_code_picker.dart

@@ -265,6 +265,7 @@ class CountryCodePickerState extends State<CountryCodePicker> {
           flagWidth: widget.flagWidth,
           size: widget.dialogSize,
           backgroundColor: widget.dialogBackgroundColor,
+          barrierColor: widget.barrierColor,
           hideSearch: widget.hideSearch,
           closeIcon: widget.closeIcon,
         ),

lib/selection_dialog.dart

@@ -19,6 +19,9 @@ class SelectionDialog extends StatefulWidget {
   /// Background color of SelectionDialog
   final Color backgroundColor;
 
+  /// Boxshaow color of SelectionDialog that matches CountryCodePicker barrier color
+  final Color barrierColor;
+
   /// elements passed as favorite
   final List<CountryCode> favoriteElements;
 
@@ -36,6 +39,7 @@ class SelectionDialog extends StatefulWidget {
     this.flagWidth = 32,
     this.size,
     this.backgroundColor,
+    this.barrierColor,
     this.hideSearch = false,
     this.closeIcon,
   })  : assert(searchDecoration != null, 'searchDecoration must not be null!'),
@@ -66,7 +70,7 @@ class _SelectionDialogState extends State<SelectionDialog> {
                 borderRadius: BorderRadius.all(Radius.circular(25.0)),
                 boxShadow: [
                   BoxShadow(
-                    color: Colors.grey.withOpacity(1),
+                    color: widget.barrierColor ?? Colors.grey.withOpacity(1),
                     spreadRadius: 5,
                     blurRadius: 7,
                     offset: Offset(0, 3), // changes position of shadow