[fix][broker] DnsResolverUtil.TTL should be greater than zero

[Technoboy-]

Motivation

When the user set DNS cache maxTTl to 0, it will throw below exception :

Caused by: java.lang.IllegalArgumentException: maxTtl : 0 (expected: > 0)
	at io.netty.util.internal.ObjectUtil.checkPositive(ObjectUtil.java:100)
	at io.netty.resolver.dns.DefaultDnsCnameCache.<init>(DefaultDnsCnameCache.java:60)
	at io.netty.resolver.dns.DnsNameResolverBuilder.newCnameCache(DnsNameResolverBuilder.java:451)
	at io.netty.resolver.dns.DnsNameResolverBuilder.build(DnsNameResolverBuilder.java:485)
	at io.netty.resolver.dns.DnsAddressResolverGroup.newNameResolver(DnsAddressResolverGroup.java:114)
	at io.netty.resolver.dns.DnsAddressResolverGroup.newResolver(DnsAddressResolverGroup.java:92)
	at io.netty.resolver.dns.DnsAddressResolverGroup.newResolver(DnsAddressResolverGroup.java:77)
	at io.netty.resolver.AddressResolverGroup.getResolver(AddressResolverGroup.java:70)

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 47.30%. Comparing base (be1d07e) to head (5e5a8b4).
⚠️ Report is 3271 commits behind head on master.

Additional details and impacted files

@@              Coverage Diff              @@
##             master   #18565       +/-   ##
=============================================
+ Coverage     36.82%   47.30%   +10.48%     
- Complexity     7842    10466     +2624     
=============================================
  Files           698      698               
  Lines         68060    68060               
  Branches       7277     7277               
=============================================
+ Hits          25062    32198     +7136     
+ Misses        39675    32271     -7404     
- Partials       3323     3591      +268     

Flag	Coverage Δ
unittests	47.30% <ø> (+10.48%)	⬆️

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see 133 files with indirect coverage changes

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[tisonkun]

LGTM. One minor suggestion.