allow null replacement character

src/sensitiveMessageFormatter.php

@@ -12,7 +12,7 @@ class sensitiveMessageFormatter extends MessageFormatter
     public function __construct(
         ?string $template = self::CLF,
         protected array $anonymizations = [],
-        protected string $replaceChar = '*'
+        protected ?string $replaceChar = null
     ) {
         $this->createReplacements($this->anonymizations);
 
@@ -22,6 +22,7 @@ class sensitiveMessageFormatter extends MessageFormatter
     protected function createReplacements(array $search = []): void
     {
         $replacements = [];
+        $this->replaceChar = $this->replaceChar ?? '*';
 
         array_map(
             function ($search) use (&$replacements) {