Reported in OpenJDK:
http://mail.openjdk.java.net/pipermail/security-dev/2018-August/017995.html
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i got these NPE on my Server. With Java:

openjdk 11-ea 2018-09-25
OpenJDK Runtime Environment 18.9 (build 11-ea+25)
OpenJDK 64-Bit Server VM 18.9 (build 11-ea+25, mixed mode)

java.lang.NullPointerException
        at java.base/sun.security.ssl.SupportedGroupsExtension$SupportedGroups.getECGenParamSpec(SupportedGroupsExtension.java:676)
        at java.base/sun.security.ssl.SupportedGroupsExtension$NamedGroup.getParameterSpec(SupportedGroupsExtension.java:454)
        at java.base/sun.security.ssl.ECDHKeyExchange$ECDHEPossession.<init>(ECDHKeyExchange.java:111)
        at java.base/sun.security.ssl.ECDHKeyExchange$ECDHEPossessionGenerator.createPossession(ECDHKeyExchange.java:231)
        at java.base/sun.security.ssl.SSLKeyExchange$T12KeyAgreement.createPossession(SSLKeyExchange.java:357)
        at java.base/sun.security.ssl.SSLKeyExchange.createPossessions(SSLKeyExchange.java:88)
        at java.base/sun.security.ssl.ServerHello$T12ServerHelloProducer.chooseCipherSuite(ServerHello.java:429)
        at java.base/sun.security.ssl.ServerHello$T12ServerHelloProducer.produce(ServerHello.java:290)
        at java.base/sun.security.ssl.SSLHandshake.produce(SSLHandshake.java:429)
        at java.base/sun.security.ssl.ClientHello$T12ClientHelloConsumer.consume(ClientHello.java:1066)
        at java.base/sun.security.ssl.ClientHello$ClientHelloConsumer.onClientHello(ClientHello.java:833)
        at java.base/sun.security.ssl.ClientHello$ClientHelloConsumer.consume(ClientHello.java:792)
        at java.base/sun.security.ssl.SSLHandshake.consume(SSLHandshake.java:390)
        at java.base/sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:445)
        at java.base/sun.security.ssl.SSLEngineImpl$DelegatedTask$DelegatedAction.run(SSLEngineImpl.java:978)
        at java.base/sun.security.ssl.SSLEngineImpl$DelegatedTask$DelegatedAction.run(SSLEngineImpl.java:958)
        at java.base/java.security.AccessController.doPrivileged(Native Method)
        at java.base/sun.security.ssl.SSLEngineImpl$DelegatedTask.run(SSLEngineImpl.java:926)