public void bulkPop(final int items) {
    checkArgument(items > 0, "number of items to pop must be greater than 0");
    if (items > size()) {
      throw new UnderflowException();
    }

    Arrays.fill(entries, top - items + 1, top + 1, null);
    top -= items;
  }
Pops the specified number of operands from the stack.

@param items the number of operands to pop off the stack
@throws IllegalArgumentException if the items to pop is negative.
@throws UnderflowException when the items to pop is greater than {@link #size()}
evm/src/main/java/org/hyperledger/besu/evm/internal/FlexStack.java