remove PoW header validation if merge is enabled (hyperledger#5538)

* remove PoW header validation if merge is enabled

Signed-off-by: garyschulte <garyschulte@gmail.com>

CHANGELOG.md

@@ -9,6 +9,7 @@
 - Add support for Shanghai changes to the GraphQL service [#5496](https://github.com/hyperledger/besu/pull/5496)
 - Unite the tx-pool CLI options under the same Tx Pool Options group in UX. [#5466](https://github.com/hyperledger/besu/issues/5466)
 - Tidy DEBUG logs by moving engine API full logging to TRACE [#5529](https://github.com/hyperledger/besu/pull/5529)
+- remove PoW validation if merge is enabled as it is not needed anymore [#5538](https://github.com/hyperledger/besu/pull/5538)
 
 ### Bug Fixes
 - check to ensure storage and transactions are not closed prior to reading/writing [#5527](https://github.com/hyperledger/besu/pull/5527) 

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

@@ -19,7 +19,6 @@
 import org.hyperledger.besu.ethereum.mainnet.feemarket.BaseFeeMarket;
 import org.hyperledger.besu.ethereum.mainnet.feemarket.FeeMarket;
 import org.hyperledger.besu.ethereum.mainnet.headervalidationrules.AncestryValidationRule;
-import org.hyperledger.besu.ethereum.mainnet.headervalidationrules.AttachedComposedFromDetachedRule;
 import org.hyperledger.besu.ethereum.mainnet.headervalidationrules.BaseFeeMarketBlockHeaderGasPriceValidationRule;
 import org.hyperledger.besu.ethereum.mainnet.headervalidationrules.CalculatedDifficultyValidationRule;
 import org.hyperledger.besu.ethereum.mainnet.headervalidationrules.ConstantFieldValidationRule;
@@ -148,17 +147,13 @@ public static BlockHeaderValidator.Builder createBaseFeeMarketValidator(
             .addRule(new ExtraDataMaxLengthValidationRule(BlockHeader.MAX_EXTRA_DATA_BYTES))
             .addRule((new BaseFeeMarketBlockHeaderGasPriceValidationRule(baseFeeMarket)));
 
-    // if merge is enabled, use the attached version of the proof of work validation rule
-    var powValidationRule =
-        new ProofOfWorkValidationRule(
-            new EpochCalculator.DefaultEpochCalculator(),
-            PoWHasher.ETHASH_LIGHT,
-            Optional.of(baseFeeMarket));
-
-    if (isMergeEnabled) {
-      builder.addRule(new AttachedComposedFromDetachedRule(powValidationRule));
-    } else {
-      builder.addRule(powValidationRule);
+    // if this is not a merged PoS network, add the proof of work validation rule:
+    if (!isMergeEnabled) {
+      builder.addRule(
+          new ProofOfWorkValidationRule(
+              new EpochCalculator.DefaultEpochCalculator(),
+              PoWHasher.ETHASH_LIGHT,
+              Optional.of(baseFeeMarket)));
     }
     return builder;
   }