Remove getbyblocknumber from flexibleprivacyprecompiledcontract (hype…

…rledger#5221)

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## PR description
This PR aims to remove the usage of getByBlockNumber from the
FlexiblePrivacyPrecompiledContract. As far as analysis shows the only
requirement is to get a protocolSpec (it doesn't matter which one)
currently it always fetches the protocolSpec for block number 1 which
can vary according to the network config. We're changing that get the
protocolSpec for block 0 which is the only block we always have the
header.

AT nonmainnet on circle CI
Pipeline - 21048

## Fixed Issue(s)
<!-- Please link to fixed issue(s) here using format: fixes #<issue
number> -->
<!-- Example: "fixes #2" -->
Fixes hyperledger#5160 

## Documentation

- [x] I thought about documentation and added the `doc-change-required`
label to this PR if
[updates are
required](https://wiki.hyperledger.org/display/BESU/Documentation).

## Acceptance Tests (Non Mainnet)

- [x] I have considered running `./gradlew acceptanceTestNonMainnet`
locally if my PR affects non-mainnet modules.

## Changelog

- [x] I thought about the changelog and included a [changelog update if
required](https://wiki.hyperledger.org/display/BESU/Changelog).

---------

Signed-off-by: Gabriel Fukushima <gabrielfukushima@gmail.com>

besu/src/main/java/org/hyperledger/besu/RunnerBuilder.java

@@ -67,6 +67,7 @@
 import org.hyperledger.besu.ethereum.api.query.PrivacyQueries;
 import org.hyperledger.besu.ethereum.blockcreation.MiningCoordinator;
 import org.hyperledger.besu.ethereum.chain.Blockchain;
+import org.hyperledger.besu.ethereum.core.BlockHeader;
 import org.hyperledger.besu.ethereum.core.MiningParameters;
 import org.hyperledger.besu.ethereum.core.PrivacyParameters;
 import org.hyperledger.besu.ethereum.core.Synchronizer;
@@ -796,7 +797,8 @@ public Runner build() {
             .build();
     vertx.deployVerticle(filterManager);
 
-    createPrivateTransactionObserver(filterManager, privacyParameters);
+    createPrivateTransactionObserver(
+        filterManager, privacyParameters, context.getBlockchain().getGenesisBlockHeader());
 
     final P2PNetwork peerNetwork = networkRunner.getNetwork();
 
@@ -1032,7 +1034,8 @@ public Runner build() {
                   DefaultAuthenticationService.create(vertx, webSocketConfiguration),
                   metricsSystem));
 
-      createPrivateTransactionObserver(subscriptionManager, privacyParameters);
+      createPrivateTransactionObserver(
+          subscriptionManager, privacyParameters, context.getBlockchain().getGenesisBlockHeader());
     }
 
     final Optional<MetricsService> metricsService =
@@ -1344,17 +1347,19 @@ private void createLogsSubscriptionService(
 
   private void createPrivateTransactionObserver(
       final PrivateTransactionObserver privateTransactionObserver,
-      final PrivacyParameters privacyParameters) {
+      final PrivacyParameters privacyParameters,
+      final BlockHeader genesisBlockHeader) {
     // register privateTransactionObserver as observer of events fired by the flexible precompile.
     if (privacyParameters.isFlexiblePrivacyGroupsEnabled()
         && privacyParameters.isMultiTenancyEnabled()) {
       final FlexiblePrivacyPrecompiledContract flexiblePrivacyPrecompiledContract =
           (FlexiblePrivacyPrecompiledContract)
               besuController
                   .getProtocolSchedule()
-                  .getByBlockNumber(1)
+                  .getByBlockHeader(genesisBlockHeader)
                   .getPrecompileContractRegistry()
                   .get(FLEXIBLE_PRIVACY);
+
       flexiblePrivacyPrecompiledContract.addPrivateTransactionObserver(privateTransactionObserver);
     }
   }