7311: Refactor peer task system usage in DownloadReceiptsStep to better match old system

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

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

@@ -37,9 +37,6 @@ import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 import java.util.function.Function;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 public class DownloadReceiptsStep
     implements Function<List<Block>, CompletableFuture<List<BlockWithReceipts>>> {
 
@@ -65,18 +62,26 @@ public class DownloadReceiptsStep
     if (synchronizerConfiguration.isPeerTaskSystemEnabled()) {
       return ethContext
           .getScheduler()
-          .scheduleServiceTask(
+          .scheduleServiceTask(() -> getReceiptsWithPeerTaskSystem(headers))
-              () -> {
+          .thenApply((receipts) -> combineBlocksAndReceipts(blocks, receipts));
+
+    } else {
+      return GetReceiptsForHeadersTask.forHeaders(ethContext, headers, metricsSystem)
+          .run()
+          .thenApply((receipts) -> combineBlocksAndReceipts(blocks, receipts));
+    }
+  }
+
+  private CompletableFuture<Map<BlockHeader, List<TransactionReceipt>>>
+      getReceiptsWithPeerTaskSystem(final List<BlockHeader> headers) {
     Map<BlockHeader, List<TransactionReceipt>> getReceipts = new HashMap<>();
     do {
-                  GetReceiptsFromPeerTask task =
+      GetReceiptsFromPeerTask task = new GetReceiptsFromPeerTask(headers, new BodyValidator());
-                      new GetReceiptsFromPeerTask(headers, new BodyValidator());
+      PeerTaskExecutorResult<Map<BlockHeader, List<TransactionReceipt>>> getReceiptsResult =
-                  PeerTaskExecutorResult<Map<BlockHeader, List<TransactionReceipt>>>
+          peerTaskExecutor.execute(task);
-                      getReceiptsResult = peerTaskExecutor.execute(task);
       if (getReceiptsResult.responseCode() == PeerTaskExecutorResponseCode.SUCCESS
           && getReceiptsResult.result().isPresent()) {
-                    Map<BlockHeader, List<TransactionReceipt>> taskResult =
+        Map<BlockHeader, List<TransactionReceipt>> taskResult = getReceiptsResult.result().get();
-                        getReceiptsResult.result().get();
         taskResult
             .keySet()
             .forEach(
@@ -93,15 +98,7 @@ public class DownloadReceiptsStep
       headers.removeAll(getReceipts.keySet());
       // repeat until all headers have receipts
     } while (!headers.isEmpty());
-                return CompletableFuture.completedFuture(
+    return CompletableFuture.completedFuture(getReceipts);
-                    combineBlocksAndReceipts(blocks, getReceipts));
-              });
-
-    } else {
-      return GetReceiptsForHeadersTask.forHeaders(ethContext, headers, metricsSystem)
-          .run()
-          .thenApply((receipts) -> combineBlocksAndReceipts(blocks, receipts));
-    }
   }
 
   private List<BlockWithReceipts> combineBlocksAndReceipts(