Set min required jenkins version to 2.138.4

Author: rguenthe

pom.xml

@@ -9,7 +9,7 @@
     </parent>
 
     <properties>
-        <jenkins.version>2.164.1</jenkins.version>
+        <jenkins.version>2.138.4</jenkins.version>
         <java.level>8</java.level>
     </properties>