allow MDC have callable param

src/main/php/pattern/LoggerPatternConverter.php

diff --git a/src/main/php/pattern/LoggerPatternConverter.php b/src/main/php/pattern/LoggerPatternConverter.php
index 3e3ee3c..f4d868e 100644
--- a/src/main/php/pattern/LoggerPatternConverter.php
+++ b/src/main/php/pattern/LoggerPatternConverter.php
@@ -101,6 +101,10 @@
 			return;

 		}

 		

+		if ($string instanceof Closure) {

+			$string = ($string)();

+		}

+		

 		$len = strlen($string);

 	

 		// Trim the string if needed