Smack fails under JDK 11 because com.sun.jndi.dns.DnsContextFactory is not inaccessible

The change was reverted as it breaks smack-resolver-javax.

It appears the right fix is for Java 11 modules to declare a dependency to "sun.jdk", or to use smack-resolver-minidns.

See also

• https://issues.jboss.org/browse/ISPN-9534

• https://github.com/infinispan/infinispan/pull/6267