Print full exception when NatService fails to configure automaticially (#4023)

https://github.com/hyperledger/besu/issues/3787

Signed-off-by: Antony Denyer <git@antonydenyer.co.uk>

nat/src/main/java/org/hyperledger/besu/nat/NatService.java

@@ -97,7 +97,7 @@ public class NatService {
       } catch (Exception e) {
         LOG.warn(
             "Nat manager failed to configure itself automatically due to the following reason : {}. {}",
-            e.getMessage(),
+            e,
             (fallbackEnabled)
                 ? "NONE mode will be used as a fallback (set --Xnat-method-fallback-enabled=false to disable)"
                 : "");