ISSUE-15349: DnsResolverUtil "Cannot get DNS TTL settings from sun.net.InetAddressCachePolicy class" in Java 17

[sijie]

Original Issue: apache#15349

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Describe the bug

DnsResolverUtil fails to get existing DNS TTL settings. This happens in Java 17. Error message:

WARN  org.apache.pulsar.common.util.netty.DnsResolverUtil - Cannot get DNS TTL settings from sun.net.InetAddressCachePolicy class
  java.lang.IllegalAccessException: class org.apache.pulsar.common.util.netty.DnsResolverUtil cannot access class sun.net.InetAddressCachePolicy (in module java.base) because module java.base does not export sun.net to unnamed module @3932c79a
  	at jdk.internal.reflect.Reflection.newIllegalAccessException(Reflection.java:392) ~[?:?]
  	at java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:674) ~[?:?]
  	at java.lang.reflect.Method.invoke(Method.java:560) ~[?:?]
  	at org.apache.pulsar.common.util.netty.DnsResolverUtil.<clinit>(DnsResolverUtil.java:46) ~[org.apache.pulsar-pulsar-common-2.11.0-SNAPSHOT.jar:2.11.0-SNAPSHOT]
  	at org.apache.pulsar.client.impl.ConnectionPool.createDnsNameResolver(ConnectionPool.java:116) ~[org.apache.pulsar-pulsar-client-original-2.11.0-SNAPSHOT.jar:2.11.0-SNAPSHOT]

To Reproduce

Use Pulsar Java Client in Java 17

Expected behavior

Pulsar Java Client should be able to detect DNS TTL settings used in Java and apply them to Netty's DnsNameResolverBuilder.

Additional context
apache#15219

[z81690074]

我也遇到这个问题了，可以正常使用pulsar,但是启动会抛这个异常