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>0.11.15</version>
+	<version>0.11.16</version>
 	<name>Web4Rail</name>
 	<packaging>jar</packaging>
 	<description>Java Model Railway Control</description>

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

@@ -211,6 +211,8 @@ public class Application extends BaseClass{
 			OutputStream out = client.getResponseBody();
 			FileInputStream in = new FileInputStream(file);
 			in.transferTo(out);
+			out.flush();
+			LOG.debug("transferred file");
 			in.close();
 			out.close();
 			return;