NPE occurs if additional logging is enabled with "java.net.http.HttpClient.log" system property:

java.lang.NullPointerException
at java.net.http.AsyncSSLDelegate.logParams(java.httpclient@9-internal/AsyncSSLDelegate.java:570)
at java.net.http.AsyncSSLDelegate.<init>(java.httpclient@9-internal/AsyncSSLDelegate.java:148)
at java.net.http.AsyncSSLConnection.<init>(java.httpclient@9-internal/AsyncSSLConnection.java:43)
at java.net.http.HttpConnection.getSSLConnection(java.httpclient@9-internal/HttpConnection.java:161)
at java.net.http.HttpConnection.getConnectionImpl(java.httpclient@9-internal/HttpConnection.java:196)
at java.net.http.HttpConnection.getConnection(java.httpclient@9-internal/HttpConnection.java:95)
at java.net.http.Http2Connection.<init>(java.httpclient@9-internal/Http2Connection.java:175)
at java.net.http.Http2ClientImpl.getConnectionFor(java.httpclient@9-internal/Http2ClientImpl.java:99)
at java.net.http.ExchangeImpl.get(java.httpclient@9-internal/ExchangeImpl.java:64)
at java.net.http.Exchange.responseImpl0(java.httpclient@9-internal/Exchange.java:134)
at java.net.http.Exchange.responseImpl(java.httpclient@9-internal/Exchange.java:127)
at java.net.http.Exchange.response(java.httpclient@9-internal/Exchange.java:84)
at java.net.http.MultiExchange.response(java.httpclient@9-internal/MultiExchange.java:98)
at java.net.http.HttpRequestImpl.response(java.httpclient@9-internal/HttpRequestImpl.java:212)
at TLSConnection.connect(TLSConnection.java:136)
at TLSConnection.lambda$main$1(TLSConnection.java:81)
at TLSConnection.expectSuccess(TLSConnection.java:145)
at TLSConnection.main(TLSConnection.java:79)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(java.base@9-internal/Native Method)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(java.base@9-internal/NativeMethodAccessorImpl.java:62)
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(java.base@9-internal/DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(java.base@9-internal/Method.java:531)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:110)
at java.lang.Thread.run(java.base@9-internal/Thread.java:804)


It happens because AsyncSSLDelegate.logParams(SSLParameters) doesn't check for null values which were returned by SSLParameters instance.