Add http response message (and log some details)

CHANGELOG.md

@@ -27,6 +27,7 @@ Note that this project **does not** adhere to [Semantic Versioning](https://semv
 - We replaced the word "Key bindings" with "Keyboard shortcuts" in the Preferences tab. [#11153](https://github.com/JabRef/jabref/pull/11153)
 - We slightly improved the duplicate check if ISBNs are present. [#8885](https://github.com/JabRef/jabref/issues/8885)
 - JabRef no longer downloads HTML files of websites when a PDF was not found. [#10149](https://github.com/JabRef/jabref/issues/10149)
+- We added the HTTP message (in addition to the response code) if an error is encountered.
 
 ### Fixed
 

src/main/java/org/jabref/logic/net/URLDownload.java

@@ -387,9 +387,10 @@ public URLConnection openConnection() throws IOException {
         }
 
         if (connection instanceof HttpURLConnection lConnection) {
-            // normally, 3xx is redirect
+            // this does network i/o: GET + read returned headers
             int status = lConnection.getResponseCode();
 
+            // normally, 3xx is redirect
             if ((status == HttpURLConnection.HTTP_MOVED_TEMP)
                 || (status == HttpURLConnection.HTTP_MOVED_PERM)
                 || (status == HttpURLConnection.HTTP_SEE_OTHER)) {
@@ -399,13 +400,14 @@ public URLConnection openConnection() throws IOException {
                 connection = new URLDownload(newUrl).openConnection();
             }
             if ((status >= 400) && (status < 500)) {
-                throw new IOException(new FetcherClientException("Encountered HTTP Status code " + status));
+                LOGGER.info("HTTP {}, details: {}, {}", status, lConnection.getResponseMessage(), lConnection.getContentLength() > 0 ? lConnection.getContent() : "");
+                throw new IOException(new FetcherClientException("Encountered HTTP %s %s".formatted(status, lConnection.getResponseMessage())));
             }
             if (status >= 500) {
-                throw new IOException(new FetcherServerException("Encountered HTTP Status Code " + status));
+                LOGGER.info("HTTP {}, details: {}, {}", status, lConnection.getResponseMessage(), lConnection.getContentLength() > 0 ? lConnection.getContent() : "");
+                throw new IOException(new FetcherServerException("Encountered HTTP %s %s".formatted(status, lConnection.getResponseMessage())));
             }
         }
-        // this does network i/o: GET + read returned headers
         return connection;
     }