7311: Handle headers with no receipts as a special case in DownloadReceiptsStep

Signed-off-by: Matilda Clerke <matilda.clerke@consensys.net>

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/sync/fastsync/DownloadReceiptsStep.java

@@ -17,6 +17,7 @@ package org.hyperledger.besu.ethereum.eth.sync.fastsync;
 import static java.util.Collections.emptyList;
 import static java.util.stream.Collectors.toList;
 
+import org.hyperledger.besu.datatypes.Hash;
 import org.hyperledger.besu.ethereum.core.Block;
 import org.hyperledger.besu.ethereum.core.BlockHeader;
 import org.hyperledger.besu.ethereum.core.BlockWithReceipts;
@@ -80,6 +81,10 @@ public class DownloadReceiptsStep
   private CompletableFuture<Map<BlockHeader, List<TransactionReceipt>>>
       getReceiptsWithPeerTaskSystem(final List<BlockHeader> headers) {
     Map<BlockHeader, List<TransactionReceipt>> getReceipts = new HashMap<>();
+    headers.stream()
+        .filter(header -> header.getReceiptsRoot().equals(Hash.EMPTY_TRIE_HASH))
+        .forEach(header -> getReceipts.put(header, emptyList()));
+    headers.removeAll(getReceipts.keySet());
     do {
       GetReceiptsFromPeerTask task =
           new GetReceiptsFromPeerTask(headers, new BodyValidator(), currentProtocolSpecSupplier);

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/sync/tasks/GetReceiptsForHeadersTask.java

@@ -65,6 +65,7 @@ public class GetReceiptsForHeadersTask
     completeEmptyReceipts(headers);
   }
 
+  // TODO: This is only used in test code and should be removed
   public static GetReceiptsForHeadersTask forHeaders(
       final EthContext ethContext,
       final List<BlockHeader> headers,

ethereum/eth/src/test/java/org/hyperledger/besu/ethereum/eth/sync/fastsync/DownloadReceiptsStepTest.java

@@ -18,6 +18,7 @@ import static java.util.Arrays.asList;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.mock;
 
+import org.hyperledger.besu.datatypes.Hash;
 import org.hyperledger.besu.ethereum.ProtocolContext;
 import org.hyperledger.besu.ethereum.chain.MutableBlockchain;
 import org.hyperledger.besu.ethereum.core.Block;
@@ -156,6 +157,7 @@ public class DownloadReceiptsStepTest {
     final Block block = Mockito.mock(Block.class);
     final BlockHeader blockHeader = Mockito.mock(BlockHeader.class);
     Mockito.when(block.getHeader()).thenAnswer((invocationOnMock) -> blockHeader);
+    Mockito.when(blockHeader.getReceiptsRoot()).thenReturn(Hash.fromHexStringLenient("DEADBEEF"));
     final BlockBody blockBody = Mockito.mock(BlockBody.class);
     Mockito.when(block.getBody()).thenAnswer((invocationOnMock) -> blockBody);
     Mockito.when(blockBody.getTransactions())