code: @Override
  	public int getMinPrefixLengthForBlock() {
  		Integer result;
  		if(hasNoPrefixCache() || (result = prefixCache.cachedMinPrefix) == null) {
  			prefixCache.cachedMinPrefix = result = cacheBits(super.getMinPrefixLengthForBlock());
  		}
  		return result;
  	}
docs: Returns the smallest CIDR prefix length possible (largest network) for which this includes the block of address sections for that prefix.
  
  @see inet.ipaddr.format.standard.IPAddressDivision#getBlockMaskPrefixLength(boolean)
  
  @return