Fix: Fallback to getName when canonicalName is null in BlockHeaderValidator DEBUG log (#6332)

* fallback to simple name when canonical name is null
* use getName instead of getSimpleName to include the package name

Signed-off-by: Manoj P R <manojpramesh@gmail.com>

---------

Signed-off-by: Manoj P R <manojpramesh@gmail.com>
Co-authored-by: Sally MacFarlane <macfarla.github@gmail.com>

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/BlockHeaderValidator.java

@@ -84,7 +84,10 @@ public class BlockHeaderValidator {
             rule -> {
               boolean worked = rule.validate(header, parent, protocolContext);
               if (!worked) {
-                LOG.debug("{} rule failed", rule.innerRuleClass().getCanonicalName());
+                String canonicalName = rule.innerRuleClass().getCanonicalName();
+                LOG.debug(
+                    "{} rule failed",
+                    canonicalName == null ? rule.innerRuleClass().getName() : canonicalName);
               }
               return worked;
             });