@Override
  public String toString() {
    return "BlockPropagationManager{"
        + processingBlocksManager
        + ", pendingBlocksManager="
        + pendingBlocksManager
        + '}';
  }
Try to request the lowest ancestor for the given pending block or process the descendants if
the ancestor is already in the chain
ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/sync/BlockPropagationManager.java