figuring out, what is wrong with maven-built jar

pom.xml

@@ -4,7 +4,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>de.srsoftware</groupId>
 	<artifactId>web4rail</artifactId>
-	<version>0.11.17</version>
+	<version>0.11.18</version>
 	<name>Web4Rail</name>
 	<packaging>jar</packaging>
 	<description>Java Model Railway Control</description>

src/main/java/de/srsoftware/web4rail/Application.java

@@ -207,8 +207,11 @@ public class Application extends BaseClass{
 		LOG.debug("requesting file: {}",file);
 		if (file.exists()) {
 			LOG.debug("found...");
-			client.getResponseHeaders().add("Content-Type", Files.probeContentType(file.toPath()));
+			String ct = Files.probeContentType(file.toPath());
+			client.getResponseHeaders().add("Content-Type", ct);
+			LOG.debug("Content-Type: {}",ct);
 			client.sendResponseHeaders(200, file.length());
+			LOG.debug("Length: {}",file.length());
 			OutputStream out = client.getResponseBody();
 			FileInputStream in = new FileInputStream(file);
 			in.transferTo(out);