Add accept-language header for MPL license (#22395)

sdks/java/container/license_scripts/pull_licenses_java.py

@@ -55,7 +55,12 @@ def pull_from_url(file_name, url, dep, no_list):
         logging.info('Replaced local file URL with {url} for {dep}'.format(url=url, dep=dep))
 
     try:
-        url_read = urlopen(Request(url, headers={'User-Agent': 'Apache Beam'}))
+        url_read = urlopen(Request(url, headers={
+            'User-Agent': 'Apache Beam',
+            # MPL license fails to resolve redirects without this header
+            # see https://github.com/apache/beam/issues/22394
+            'accept-language': 'en-US,en;q=0.9',
+        }))
         with open(file_name, 'wb') as temp_write:
             shutil.copyfileobj(url_read, temp_write)
         logging.debug(