Gardening: Streamline SeedNode.toString()

Motivation
----------
Want seed nodes to be easier to read when they
appear in the logs.

Modifications
-------------
Omit absent ports from toString()

Example output after this change:

SeedNode{address='example.com'}
SeedNode{address='example.com', kvPort=1234}
SeedNode{address='example.com', kvPort=1234, mgmtPort=5678}

Change-Id: I1e63b8214ef9102c645cb2e1ba5e26ce099e17d6
Reviewed-on: https://review.couchbase.org/c/couchbase-jvm-clients/+/213545
Tested-by: Build Bot <[email protected]>
Reviewed-by: Graham Pople <[email protected]>

Author: dnault

core-io/src/main/java/com/couchbase/client/core/env/SeedNode.java

@@ -151,12 +151,14 @@ public Optional<Integer> protostellarPort() {
 
   @Override
   public String toString() {
-    return "SeedNode{" +
-      "address='" + address + '\'' +
-      ", kvPort=" + kvPort +
-      ", mgmtPort=" + clusterManagerPort +
-      ", psPort=" + protostellarPort +
-      '}';
+    StringBuilder sb = new StringBuilder("SeedNode{")
+      .append("address='").append(address).append('\'');
+
+    kvPort.ifPresent(port -> sb.append(", kvPort=").append(port));
+    clusterManagerPort.ifPresent(port -> sb.append(", mgmtPort=").append(port));
+    protostellarPort.ifPresent(port -> sb.append(", psPort=").append(port));
+
+    return sb.append('}').toString();
   }
 
   @Override