public List<Block> childrenOf(final Hash parentBlock) {
    final Set<Hash> blocksByParent = pendingBlocksByParentHash.get(parentBlock);
    if (blocksByParent == null || blocksByParent.size() == 0) {
      return Collections.emptyList();
    }
    return blocksByParent.stream()
        .map(pendingBlocks::get)
        .filter(Objects::nonNull)
        .map(ImmutablePendingBlock::block)
        .collect(Collectors.toList());
  }
Stop tracking the given block.

@param block the block that is no longer pending
@return true if this block was removed
ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/sync/state/PendingBlocksManager.java