Firebase calls all fail with java.util.zip.ZipException: Not in GZIP format with apache httpclient 5.6

[papegaaij]

• Operating System version: Kubuntu 25.10
• Firebase SDK version: 9.7.0
• Library version: _____
• Firebase Product: messaging

When sending a message with Firebase using Apache Httpclient 5.6, all calls fail with an exception trying to read the response. The calls do come through, but the response cannot be read. This is very likely because Httpclient 5.6 has built-in support for decompression, while Firebase performs its own decompression. This probably causes the data to be decompressed twice.

Exception in thread "main" com.google.firebase.messaging.FirebaseMessagingException: Unknown error while making a remote service call: Not in GZIP format
	at com.google.firebase.messaging.FirebaseMessagingException.withMessagingErrorCode(FirebaseMessagingException.java:51)
	at com.google.firebase.messaging.FirebaseMessagingClientImpl$MessagingErrorHandler.createException(FirebaseMessagingClientImpl.java:293)
	at com.google.firebase.messaging.FirebaseMessagingClientImpl$MessagingErrorHandler.createException(FirebaseMessagingClientImpl.java:282)
	at com.google.firebase.internal.AbstractHttpErrorHandler.handleIOException(AbstractHttpErrorHandler.java:63)
	at com.google.firebase.internal.ErrorHandlingHttpClient.send(ErrorHandlingHttpClient.java:111)
	at com.google.firebase.internal.ErrorHandlingHttpClient.sendAndParse(ErrorHandlingHttpClient.java:72)
	at com.google.firebase.messaging.FirebaseMessagingClientImpl.sendSingleRequest(FirebaseMessagingClientImpl.java:127)
	at com.google.firebase.messaging.FirebaseMessagingClientImpl.send(FirebaseMessagingClientImpl.java:113)
	at com.google.firebase.messaging.FirebaseMessaging$1.execute(FirebaseMessaging.java:142)
	at com.google.firebase.messaging.FirebaseMessaging$1.execute(FirebaseMessaging.java:139)
	at com.google.firebase.internal.CallableOperation.call(CallableOperation.java:36)
	at com.google.firebase.messaging.FirebaseMessaging.send(FirebaseMessaging.java:109)
	at com.google.firebase.messaging.FirebaseMessaging.send(FirebaseMessaging.java:91)
	at nl.topicus.GoogleFirebaseApp.pushToGoogle(GoogleFirebaseApp.java:110)
	at nl.topicus.GoogleFirebaseApp.main(GoogleFirebaseApp.java:79)
Caused by: java.util.zip.ZipException: Not in GZIP format
	at java.base/java.util.zip.GZIPInputStream.readHeader(GZIPInputStream.java:197)
	at java.base/java.util.zip.GZIPInputStream.<init>(GZIPInputStream.java:81)
	at java.base/java.util.zip.GZIPInputStream.<init>(GZIPInputStream.java:112)
	at com.google.api.client.http.GzipSupport.newGzipInputStream(GzipSupport.java:13)
	at com.google.api.client.http.HttpResponse.getContent(HttpResponse.java:364)
	at com.google.firebase.internal.ErrorHandlingHttpClient.send(ErrorHandlingHttpClient.java:101)
	... 10 more