SDK updates break Webworks File Upload

I have a JiraWebActionSupport class with this code to get file upload:

		HttpServletRequest wrapperReq = ServletActionContext.getRequest();
		if (wrapperReq != null && wrapperReq instanceof MultiPartRequestWrapper) {
			MultiPartRequestWrapper mpr = (MultiPartRequestWrapper) wrapperReq;
			LOGGER.debug("Filenames found: ");
			Enumeration fileNames = mpr.getFileNames();
			while (fileNames.hasMoreElements()) {
				String s = String.valueOf(fileNames.nextElement());
				LOGGER.debug(s + ": " + mpr.getFile(s) + "; " + mpr.getFilesystemName(s));
			}			
		}

It was working yesterday.

But today my plugin SDK’s 3-day license is about to expire. So I restarted the server, and SDK downlaoded some updates. Now the file upload fails, .getFile() will return null.

I got these debug output:

2023-03-29 10:51:01,706 http-nio-2990-exec-3 DEBUG admin 651x11467x1 tmit1t 0:0:0:0:0:0:0:1 /secure/admin/plugins/handler/ExportAction2.jspa [c.igsl.configmigration.ExportAction2] doExecute
2023-03-29 10:51:01,706 http-nio-2990-exec-3 DEBUG admin 651x11467x1 tmit1t 0:0:0:0:0:0:0:1 /secure/admin/plugins/handler/ExportAction2.jspa [c.igsl.configmigration.ExportAction2] Filenames found: 
2023-03-29 10:51:01,706 http-nio-2990-exec-3 DEBUG admin 651x11467x1 tmit1t 0:0:0:0:0:0:0:1 /secure/admin/plugins/handler/ExportAction2.jspa [c.igsl.configmigration.ExportAction2] importFile: null; Server All Objects.json

MultipartRequest gave me the expected filename, but cannot get the file object.