[fix][broker] DnsResolverUtil.TTL should be greater than zero (#18565)

(cherry picked from commit 67f9461)

pulsar-common/src/main/java/org/apache/pulsar/common/util/netty/DnsResolverUtil.java

@@ -50,12 +50,8 @@ public class DnsResolverUtil {
                  | IllegalAccessException e) {
             log.warn("Cannot get DNS TTL settings from sun.net.InetAddressCachePolicy class", e);
         }
-        TTL = useDefaultTTLWhenSetToForever(ttl, DEFAULT_TTL);
-        NEGATIVE_TTL = useDefaultTTLWhenSetToForever(negativeTtl, DEFAULT_NEGATIVE_TTL);
-    }
-
-    private static int useDefaultTTLWhenSetToForever(int ttl, int defaultTtl) {
-        return ttl < 0 ? defaultTtl : ttl;
+        TTL = ttl <= 0 ? DEFAULT_TTL : ttl;
+        NEGATIVE_TTL = negativeTtl < 0 ? DEFAULT_NEGATIVE_TTL : negativeTtl;
     }
 
     private DnsResolverUtil() {

pulsar-common/src/test/java/org/apache/pulsar/common/util/netty/DnsResolverTest.java

@@ -0,0 +1,41 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.pulsar.common.util.netty;
+
+import io.netty.channel.EventLoop;
+import io.netty.resolver.dns.DnsNameResolverBuilder;
+import org.mockito.Mockito;
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+public class DnsResolverTest {
+
+    @Test
+    public void testMaxTtl() {
+        EventLoop eventLoop = Mockito.mock(EventLoop.class);
+        DnsNameResolverBuilder dnsNameResolverBuilder = new DnsNameResolverBuilder(eventLoop);
+        DnsResolverUtil.applyJdkDnsCacheSettings(dnsNameResolverBuilder);
+        // If the maxTtl is <=0, it will throw IllegalArgumentException.
+        try {
+            dnsNameResolverBuilder.build();
+        } catch (Exception ex) {
+            Assert.assertFalse(ex instanceof IllegalArgumentException);
+        }
+    }
+}