try to fix problem with mutaded vowel on linux distribution

oKBereitschaftsplanungBackend/src/main/java/org/eclipse/openk/sp/controller/reports/ReportController.java

diff --git a/oKBereitschaftsplanungBackend/src/main/java/org/eclipse/openk/sp/controller/reports/ReportController.java b/oKBereitschaftsplanungBackend/src/main/java/org/eclipse/openk/sp/controller/reports/ReportController.java
index 86de489..edf32f5 100644
--- a/oKBereitschaftsplanungBackend/src/main/java/org/eclipse/openk/sp/controller/reports/ReportController.java
+++ b/oKBereitschaftsplanungBackend/src/main/java/org/eclipse/openk/sp/controller/reports/ReportController.java
@@ -431,8 +431,8 @@
 
 		String token = String.valueOf(new Random().nextLong());
 
-		try (InputStream rptdFileStream = new FileInputStream(
-				fileHelper.loadFileFromFileSystemOrResource(reportDirectory, reportName + ".rptdesign", true))) {
+		try (InputStream rptdFileStream = new FileInputStream(fileHelper.loadFileFromFileSystemOrResource(
+				reportDirectory, new String(reportName.getBytes(StandardCharsets.ISO_8859_1)) + ".rptdesign", true))) {
 			LOGGER.info("Found design file " + reportName + ".rptdesign. inside " + reportDirectory);
 
 			IReportEngine engine = initialiseBirtEngine();