FULL PRODUCT VERSION :
tested with Oracle Java 9.0.4+11 and 1.8.0_162-b12

ADDITIONAL OS VERSION INFORMATION :
Darwin Nicolass-MacBook-Pro.local 17.3.0 Darwin Kernel Version 17.3.0: Thu Nov 9 18:09:22 PST 2017; root:xnu-4570.31.3~1/RELEASE_X86_64 x86_64

A DESCRIPTION OF THE PROBLEM :
I got the following error when I execute concurrent calls as a first call.

If only one call is executed alone and then concurrent calls are executed it works fine.

I suspect a thread safety error during the initialization of an object.
javax.ws.rs.ProcessingException: 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 org.glassfish.jersey.client.internal.HttpUrlConnector.apply(HttpUrlConnector.java:284)
at org.glassfish.jersey.client.ClientRuntime.invoke(ClientRuntime.java:278)
at org.glassfish.jersey.client.JerseyInvocation.lambda$invoke$2(JerseyInvocation.java:787)
at org.glassfish.jersey.internal.Errors.process(Errors.java:316)
at org.glassfish.jersey.internal.Errors.process(Errors.java:298)
at org.glassfish.jersey.internal.Errors.process(Errors.java:229)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:414)
at org.glassfish.jersey.client.JerseyInvocation.invoke(JerseyInvocation.java:785)
at org.glassfish.jersey.client.JerseyInvocation$Builder.method(JerseyInvocation.java:438)
at org.glassfish.jersey.client.proxy.WebResourceFactory.invoke(WebResourceFactory.java:355)
at com.ingenico.gs.esf.http.jetty.client.ClientProxyProvider.invokeRemoteProxy(ClientProxyProvider.java:27)
at com.ingenico.gs.esf.http.jetty.client.RetryableProxyService.invoke(RetryableProxyService.java:98)
at com.sun.proxy.$Proxy143.signature(Unknown Source)
at com.ingenico.gs.esf.http.jetty.authentication.AuthenticationKeyManagementClient.lambda$newKeyIfAbsent$3(AuthenticationKeyManagementClient.java:148)
at com.ingenico.gs.esf.cache.api.Cache.computeIfAbsent(Cache.java:104)
at com.ingenico.gs.esf.http.jetty.authentication.AuthenticationKeyManagementClient.newKeyIfAbsent(AuthenticationKeyManagementClient.java:147)
at com.ingenico.gs.esf.http.jetty.authentication.AuthenticationKeyManagementClient.getKey(AuthenticationKeyManagementClient.java:131)
at com.ingenico.gs.esf.http.jetty.authentication.AuthenticationKeyManagementClient.getRequestSignatureKey(AuthenticationKeyManagementClient.java:100)
at com.ingenico.gs.esf.http.api.hmac.SignatureService.sign(SignatureService.java:95)
at com.ingenico.gs.esf.http.api.client.filter.RequestSignatureFilter.filter(RequestSignatureFilter.java:52)
at org.glassfish.jersey.client.ClientFilteringStages$RequestFilteringStage.apply(ClientFilteringStages.java:108)
at org.glassfish.jersey.client.ClientFilteringStages$RequestFilteringStage.apply(ClientFilteringStages.java:96)
at org.glassfish.jersey.process.internal.Stages.process(Stages.java:171)
at org.glassfish.jersey.client.ClientRuntime.invoke(ClientRuntime.java:278)
at org.glassfish.jersey.client.JerseyInvocation.lambda$invoke$2(JerseyInvocation.java:787)
at org.glassfish.jersey.internal.Errors.process(Errors.java:316)
at org.glassfish.jersey.internal.Errors.process(Errors.java:298)
at org.glassfish.jersey.internal.Errors.process(Errors.java:229)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:414)
at org.glassfish.jersey.client.JerseyInvocation.invoke(JerseyInvocation.java:785)
at org.glassfish.jersey.client.JerseyInvocation$Builder.method(JerseyInvocation.java:438)
at org.glassfish.jersey.client.proxy.WebResourceFactory.invoke(WebResourceFactory.java:355)
at com.sun.proxy.$Proxy140.ping(Unknown Source)
at com.ingenico.gs.esf.http.jetty.testtools.server.SetupTest.lambda$null$0(SetupTest.java:152)
at java.lang.Thread.run(Thread.java:748)
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 sun.security.ssl.Alerts.getSSLException(Alerts.java:203)
at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1959)
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302)
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:296)
at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1595)
at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:220)
at sun.security.ssl.Handshaker.processLoop(Handshaker.java:1026)
at sun.security.ssl.Handshaker.process_record(Handshaker.java:961)
at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1072)
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1385)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1413)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1397)
at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:559)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1564)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1492)
at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:480)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getResponseCode(HttpsURLConnectionImpl.java:347)
at org.glassfish.jersey.client.internal.HttpUrlConnector._apply(HttpUrlConnector.java:390)
at org.glassfish.jersey.client.internal.HttpUrlConnector.apply(HttpUrlConnector.java:282)
... 34 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 sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:397)
at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:302)
at sun.security.validator.Validator.validate(Validator.java:260)
at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:324)
at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:229)
at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:124)
at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1577)
... 49 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
at sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:141)
at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:126)
at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:280)
at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:392)
... 55 more

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
mvn test -Dtest=Http2Test#testConcurrentHttp1 with repository https://github.com/nhenneaux/jersey-http2-jetty-connector

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
no error and exception during the test
ACTUAL -
Exception
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)
... 36 more

ERROR MESSAGES/STACK TRACES THAT OCCUR :
javax.ws.rs.ProcessingException: 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 org.glassfish.jersey.client.internal.HttpUrlConnector.apply(HttpUrlConnector.java:284)
at org.glassfish.jersey.client.ClientRuntime.invoke(ClientRuntime.java:278)
at org.glassfish.jersey.client.JerseyInvocation.lambda$invoke$2(JerseyInvocation.java:787)
at org.glassfish.jersey.internal.Errors.process(Errors.java:316)
at org.glassfish.jersey.internal.Errors.process(Errors.java:298)
at org.glassfish.jersey.internal.Errors.process(Errors.java:229)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:414)
at org.glassfish.jersey.client.JerseyInvocation.invoke(JerseyInvocation.java:785)
at org.glassfish.jersey.client.JerseyInvocation$Builder.method(JerseyInvocation.java:438)
at org.glassfish.jersey.client.proxy.WebResourceFactory.invoke(WebResourceFactory.java:355)
at com.sun.proxy.$Proxy46.hello(Unknown Source)
at org.glassfish.jersey.jetty.connector.Http2Test.lambda$testConcurrent$0(Http2Test.java:247)
at java.base/java.lang.Thread.run(Thread.java:844)
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:1969)
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:1092)
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.getInputStream0(HttpURLConnection.java:1581)
at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1509)
at java.base/java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:527)
at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.getResponseCode(HttpsURLConnectionImpl.java:329)
at org.glassfish.jersey.client.internal.HttpUrlConnector._apply(HttpUrlConnector.java:390)
at org.glassfish.jersey.client.internal.HttpUrlConnector.apply(HttpUrlConnector.java:282)
... 12 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)
... 30 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)
... 36 more
javax.ws.rs.ProcessingException: 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 org.glassfish.jersey.client.internal.HttpUrlConnector.apply(HttpUrlConnector.java:284)
at org.glassfish.jersey.client.ClientRuntime.invoke(ClientRuntime.java:278)
at org.glassfish.jersey.client.JerseyInvocation.lambda$invoke$2(JerseyInvocation.java:787)
at org.glassfish.jersey.internal.Errors.process(Errors.java:316)
at org.glassfish.jersey.internal.Errors.process(Errors.java:298)
at org.glassfish.jersey.internal.Errors.process(Errors.java:229)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:414)
at org.glassfish.jersey.client.JerseyInvocation.invoke(JerseyInvocation.java:785)
at org.glassfish.jersey.client.JerseyInvocation$Builder.method(JerseyInvocation.java:438)
at org.glassfish.jersey.client.proxy.WebResourceFactory.invoke(WebResourceFactory.java:355)
at com.sun.proxy.$Proxy46.hello(Unknown Source)
at org.glassfish.jersey.jetty.connector.Http2Test.lambda$testConcurrent$0(Http2Test.java:247)
at java.base/java.lang.Thread.run(Thread.java:844)
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:1969)
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:1092)
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.getInputStream0(HttpURLConnection.java:1581)
at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1509)
at java.base/java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:527)
at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.getResponseCode(HttpsURLConnectionImpl.java:329)
at org.glassfish.jersey.client.internal.HttpUrlConnector._apply(HttpUrlConnector.java:390)
at org.glassfish.jersey.client.internal.HttpUrlConnector.apply(HttpUrlConnector.java:282)
... 12 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)
... 30 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)
... 36 more
javax.ws.rs.ProcessingException: 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 org.glassfish.jersey.client.internal.HttpUrlConnector.apply(HttpUrlConnector.java:284)
at org.glassfish.jersey.client.ClientRuntime.invoke(ClientRuntime.java:278)
at org.glassfish.jersey.client.JerseyInvocation.lambda$invoke$2(JerseyInvocation.java:787)
at org.glassfish.jersey.internal.Errors.process(Errors.java:316)
at org.glassfish.jersey.internal.Errors.process(Errors.java:298)
at org.glassfish.jersey.internal.Errors.process(Errors.java:229)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:414)
at org.glassfish.jersey.client.JerseyInvocation.invoke(JerseyInvocation.java:785)
at org.glassfish.jersey.client.JerseyInvocation$Builder.method(JerseyInvocation.java:438)
at org.glassfish.jersey.client.proxy.WebResourceFactory.invoke(WebResourceFactory.java:355)
at com.sun.proxy.$Proxy46.hello(Unknown Source)
at org.glassfish.jersey.jetty.connector.Http2Test.lambda$testConcurrent$0(Http2Test.java:247)
at java.base/java.lang.Thread.run(Thread.java:844)
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:1969)
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:1092)
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.getInputStream0(HttpURLConnection.java:1581)
at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1509)
at java.base/java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:527)
at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.getResponseCode(HttpsURLConnectionImpl.java:329)
at org.glassfish.jersey.client.internal.HttpUrlConnector._apply(HttpUrlConnector.java:390)
at org.glassfish.jersey.client.internal.HttpUrlConnector.apply(HttpUrlConnector.java:282)
... 12 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)
... 30 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)
... 36 more

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
https://github.com/nhenneaux/jersey-http2-jetty-connector
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Make a first call before doing concurrent calls on the server