fix(thumbnail): generation for zip file

[alperozturk96]

Issue

Thumbnail should not be downloaded for zip file.

2026-06-11 10:38:23.146  1971-3020  ThumbnailsCacheManager  com.nextcloud.client  E
Exception downloading thumbnail for file: 2GB_file.zip

java.net.SocketTimeoutException: Read timed out
    at java.net.SocketInputStream.socketRead0(Native Method)
    at java.net.SocketInputStream.socketRead(SocketInputStream.java:118)
    at java.net.SocketInputStream.read(SocketInputStream.java:173)
    at java.net.SocketInputStream.read(SocketInputStream.java:143)
    at org.conscrypt.ConscryptEngineSocket$SSLInputStream.readFromSocket(ConscryptEngineSocket.java:920)
    at org.conscrypt.ConscryptEngineSocket$SSLInputStream.processDataFromSocket(ConscryptEngineSocket.java:884)
    at org.conscrypt.ConscryptEngineSocket$SSLInputStream.readUntilDataAvailable(ConscryptEngineSocket.java:799)
    at org.conscrypt.ConscryptEngineSocket$SSLInputStream.read(ConscryptEngineSocket.java:772)
    at java.io.BufferedInputStream.fill(BufferedInputStream.java:239)
    at java.io.BufferedInputStream.read(BufferedInputStream.java:258)
    at org.apache.commons.httpclient.HttpParser.readRawLine(HttpParser.java:78)
    at org.apache.commons.httpclient.HttpParser.readLine(HttpParser.java:106)
    at org.apache.commons.httpclient.HttpConnection.readLine(HttpConnection.java:1116)
    at org.apache.commons.httpclient.MultiThreadedHttpConnectionManager$HttpConnectionAdapter.readLine(
        MultiThreadedHttpConnectionManager.java:1413
    )
    at org.apache.commons.httpclient.HttpMethodBase.readStatusLine(HttpMethodBase.java:1973)
    at org.apache.commons.httpclient.HttpMethodBase.readResponse(HttpMethodBase.java:1735)
    at org.apache.commons.httpclient.HttpMethodBase.execute(HttpMethodBase.java:1098)
    at org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry(HttpMethodDirector.java:398)
    at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:171)
    at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:397)
    at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:323)
    at com.owncloud.android.lib.common.OwnCloudClient.executeMethod(OwnCloudClient.java:192)
    at com.owncloud.android.lib.common.OwnCloudClient.executeMethod(OwnCloudClient.java:155)
    at com.owncloud.android.datamodel.ThumbnailsCacheManager$ThumbnailGenerationTask
        .doThumbnailFromOCFileInBackground(ThumbnailsCacheManager.java:662)
    at com.owncloud.android.datamodel.ThumbnailsCacheManager$ThumbnailGenerationTask
        .doInBackground(ThumbnailsCacheManager.java:507)
    at com.owncloud.android.datamodel.ThumbnailsCacheManager$ThumbnailGenerationTask
        .doInBackground(ThumbnailsCacheManager.java:428)
    at android.os.AsyncTask$3.call(AsyncTask.java:394)
    at java.util.concurrent.FutureTask.run(FutureTask.java:317)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1156)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:651)
    at java.lang.Thread.run(Thread.java:1119)

2026-06-11 10:38:23.146  1971-3020  ThumbnailsCacheManager  com.nextcloud.client  W
Failed to obtain thumbnail for file: 2GB_file.zip

[alperozturk96]

/backport to stable-34.0.x

[github-actions]

blue-Light-Screenshot test failed, but no output was generated. Maybe a preliminary stage failed.

[github-actions]

Codacy

SpotBugs

Category	Base	New
Bad practice	33	33
Correctness	67	67
Dodgy code	215	226
Experimental	1	1
Internationalization	7	7
Malicious code vulnerability	2	2
Multithreaded correctness	31	31
Performance	41	41
Security	16	16
Total	413	424

SpotBugs increased!

[github-actions]

APK file: https://github.com/nextcloud/android/actions/runs/27347854657/artifacts/7570239329
To test this change/fix you can simply download above APK file and install and test it in parallel to your existing Nextcloud app.
(please click on link to get QR code displayed)