The classes and interfaces in the `java.security.acl` and `javax.security.cert` packages have been superseded by replacements for a long time and are deprecated in JDK 9. Two methods `javax.net.ssl.HandshakeCompletedEvent.getPeerCertificateChain()` and `javax.net.ssl.SSLSession.getPeerCertificateChain()` are also deprecated since they return the `javax.security.cert.X509Certificate` type.