Relay Node: Android notifications do not get relayed when compiled using Java 10

[devinbileck]

While attempting to setup/run a relay node, I was encountering Error while calling FCM backend service when relaying Android notifications (see below for full stack trace) and no Android notifications were being relayed.

However, iOS notifications work fine.

At this point, it seems to be due to compiling under the new mono repo using Java 10. Whereas using the old bisq-relay repo and compiling with Java 8, Android notifications work fine.

Stack trace when receiving Android notification:

com.google.firebase.messaging.FirebaseMessagingException: Error while calling FCM backend service
        at com.google.firebase.messaging.FirebaseMessaging$1.execute(FirebaseMessaging.java:262)
        at com.google.firebase.messaging.FirebaseMessaging$1.execute(FirebaseMessaging.java:240)
        at com.google.firebase.internal.CallableOperation.call(CallableOperation.java:36)
        at com.google.firebase.messaging.FirebaseMessaging.send(FirebaseMessaging.java:157)
        at com.google.firebase.messaging.FirebaseMessaging.send(FirebaseMessaging.java:143)
        at bisq.relay.RelayService.sendAndroidMessage(RelayService.java:148)
        at bisq.relay.RelayMain.lambda$handleRelay$0(RelayMain.java:107)
        at spark.RouteImpl$1.handle(RouteImpl.java:61)
        at spark.http.matching.Routes.execute(Routes.java:61)
        at spark.http.matching.MatcherFilter.doFilter(MatcherFilter.java:127)
        at spark.embeddedserver.jetty.JettyHandler.doHandle(JettyHandler.java:50)
        at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:189)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:119)
        at org.eclipse.jetty.server.Server.handle(Server.java:517)
        at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:308)
        at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:242)
        at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:261)
        at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:95)
        at org.eclipse.jetty.io.SelectChannelEndPoint$2.run(SelectChannelEndPoint.java:75)
        at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.produceAndRun(ExecuteProduceConsume.java:213)
        at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.run(ExecuteProduceConsume.java:147)
        at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:654)
        at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:572)
        at java.base/java.lang.Thread.run(Thread.java:844)
Caused by: java.io.IOException: Error getting access token for service account:
        at com.google.auth.oauth2.ServiceAccountCredentials.refreshAccessToken(ServiceAccountCredentials.java:385)
        at com.google.auth.oauth2.OAuth2Credentials.refresh(OAuth2Credentials.java:175)
        at com.google.auth.oauth2.OAuth2Credentials.getRequestMetadata(OAuth2Credentials.java:161)
        at com.google.auth.http.HttpCredentialsAdapter.initialize(HttpCredentialsAdapter.java:96)
        at com.google.firebase.internal.FirebaseRequestInitializer.initialize(FirebaseRequestInitializer.java:46)
        at com.google.api.client.http.HttpRequestFactory.buildRequest(HttpRequestFactory.java:93)
        at com.google.api.client.http.HttpRequestFactory.buildPostRequest(HttpRequestFactory.java:133)
        at com.google.firebase.messaging.FirebaseMessaging$1.execute(FirebaseMessaging.java:250)
        ... 24 more
Caused by: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at java.base/sun.security.ssl.Alerts.getSSLException(Alerts.java:198)
        at java.base/sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1974)
        at java.base/sun.security.ssl.Handshaker.fatalSE(Handshaker.java:345)
        at java.base/sun.security.ssl.Handshaker.fatalSE(Handshaker.java:339)
        at java.base/sun.security.ssl.ClientHandshaker.checkServerCerts(ClientHandshaker.java:1968)
        at java.base/sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1777)
        at java.base/sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:264)
        at java.base/sun.security.ssl.Handshaker.processLoop(Handshaker.java:1098)
        at java.base/sun.security.ssl.Handshaker.processRecord(Handshaker.java:1026)
        at java.base/sun.security.ssl.SSLSocketImpl.processInputRecord(SSLSocketImpl.java:1137)
        at java.base/sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1074)
        at java.base/sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:973)
        at java.base/sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1402)
        at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1429)
        at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1413)
        at java.base/sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:567)
        at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
        at java.base/sun.net.www.protocol.http.HttpURLConnection.getOutputStream0(HttpURLConnection.java:1356)
        at java.base/sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1331)
        at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.getOutputStream(HttpsURLConnectionImpl.java:241)
        at com.google.api.client.http.javanet.NetHttpRequest.execute(NetHttpRequest.java:77)
        at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:981)
        at com.google.auth.oauth2.ServiceAccountCredentials.refreshAccessToken(ServiceAccountCredentials.java:383)
        ... 31 more
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at java.base/sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:385)
        at java.base/sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:290)
        at java.base/sun.security.validator.Validator.validate(Validator.java:264)
        at java.base/sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:343)
        at java.base/sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:226)
        at java.base/sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:133)
        at java.base/sun.security.ssl.ClientHandshaker.checkServerCerts(ClientHandshaker.java:1947)
        ... 49 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at java.base/sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:141)
        at java.base/sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:126)
        at java.base/java.security.cert.CertPathBuilder.build(CertPathBuilder.java:297)
        at java.base/sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:380)
        ... 55 more

[devinbileck]

This no longer appears to be an issue when compiling using Java 11.
I just deployed a new node (with a v3 Tor address) using the new mono repo.
See: #5593