Fix NullPointerException in getFileMetaEntry method for URLs with chunked transfer encoding.

components/application-mgt/io.entgra.device.mgt.core.application.mgt.core/src/main/java/io/entgra/device/mgt/core/application/mgt/core/impl/FileDownloaderServiceProvider.java

@@ -122,7 +122,10 @@ public class FileDownloaderServiceProvider {
                 }
 
                 FileMetaEntry fileMetaEntry = new FileMetaEntry();
-                fileMetaEntry.setSize(Long.parseLong(Objects.requireNonNull(response.header("Content-Length"))));
+                String contentLength = response.header("Content-Length");
+                if (contentLength != null) {
+                    fileMetaEntry.setSize(Long.parseLong(contentLength));
+                }
                 fileMetaEntry.setFileName(fileNameSegments[0]);
                 fileMetaEntry.setExtension(fileNameSegments[1]);
                 return fileMetaEntry;