Only update peer with the first and last block (hyperledger#5659)

* only update peer with the first and last block

Signed-off-by: Stefan <stefan.pingel@consensys.net>

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/manager/task/AbstractGetHeadersFromPeerTask.java

@@ -95,8 +95,9 @@ protected Optional<List<BlockHeader>> processResponse(
     BlockHeader prevBlockHeader = firstHeader;
     updatePeerChainState(peer, firstHeader);
     final int expectedDelta = reverse ? -(skip + 1) : (skip + 1);
+    BlockHeader header = null;
     for (int i = 1; i < headers.size(); i++) {
-      final BlockHeader header = headers.get(i);
+      header = headers.get(i);
       if (header.getNumber() != prevBlockHeader.getNumber() + expectedDelta) {
         // Skip doesn't match, this isn't our data
         LOG.debug("header not matching the expected number. Peer: {}", peer);
@@ -116,6 +117,11 @@ protected Optional<List<BlockHeader>> processResponse(
       }
       prevBlockHeader = header;
       headersList.add(header);
+    }
+    // if we have received more than one header we have to update the chain state with the last
+    // header as well, as the header with the highest block number can be the first or the last
+    // header.
+    if (headers.size() > 1) {
       updatePeerChainState(peer, header);
     }