mcsee

public class ServiceControlPolicy {
  private SpannerDatabase spannerDB;
  private QuotaManager quotaManager;
    
  public void applyPolicyChange(PolicyChange change) {
      if (change == null) {
          // Assuming it comes from an external API
          // Beyond your control
          change = new NullPolicyChange();
      }

mcsee

public class ServiceControlPolicy {
  private SpannerDatabase spannerDB;
  private QuotaManager quotaManager;
    
  public void applyPolicyChange(PolicyChange change) {
      // NULL POINTER: change can be null
      Policy policy = spannerDB.getPolicy(change.getPolicyId());
      // NULL POINTER: policy can be null from the database
      String quotaField = policy.getQuotaField();
      // NULL POINTER: quotaField can be null (blank field)

mcsee

def find_minimum_price(products):
    min_price = float('inf')
        
    for product in products:
        if product.price < min_price:
            # This is an essential IF, you should not remove it
            min_price = product.price
            # No accidental IF here (if min_price is None:)
    
    return min_price if min_price != float('inf') else None

mcsee

def find_minimum_price(products):
    min_price = None
    
    for product in products:
        if min_price is None:
            min_price = product.price
        elif product.price < min_price:
            min_price = product.price
    
    return min_price

mcsee

// user-api-v1.json - Version 1 (maintained)
{
  "id": 317,
  "name": "Mr Nimbus",
  "email": "[email protected]",
  "nationalities": "Brazilian,Canadian,Oceanic"
}

// user-api-v2.json - Version 2 
// (new structure, backward compatible)

mcsee

// user-api-v1.json - Original API response
{
  "id": 317,
  "name": "Mr Nimbus",
  "email": "[email protected]",
  "nationalities": "Brazilian,Canadian,Oceanic"
}

// Later changed to this without versioning:
{

mcsee

use axum::{
  http::StatusCode,
  response::Json,
  routing::post,
  Router,
};
use serde_json::{json, Value};

async fn process_payment(
  Json(payload): Json<Value>

mcsee

use axum::{
  http::StatusCode,
  response::Json,
  routing::post,
  Router,
};
use serde_json::{json, Value};

async fn process_payment(
  Json(payload): Json<Value>

mcsee

public class ShoppingCart {
    private final List<Item> items = new ArrayList<>();
  
    // This version uses Optionals
    // Not all programming languages support this feature
    private Optional<Coupon> coupon = Optional.empty();

    public void addItem(Item item) {
        items.add(item);
    }

mcsee

public class ShoppingCart {
  private List<Item> items = new ArrayList<>();
    
  // 1. Identify nullable optional attributes
  // that could be collections
  // 2. Replace single nullable objects with empty collections
  private List<Coupon> coupons = new ArrayList<>();
    
  public void addItem(Item item) {
      this.items.add(item);