Validate nulls properly

Always use appropriate null validation mechanisms to prevent NullPointerExceptions and ensure code robustness.

For string parameters:

• Use Assert.hasText(profile, "Profile must have text") instead of Assert.notNull() when you need to validate both null and empty strings
• This handles both null checks and empty string validation in one call

For equals methods:

• Always check for null before comparing class types:

  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
        return true;
    }
    if (obj == null || getClass() != obj.getClass()) {
        return false;
    }
    // Continue with comparison
  }
  

For collections and arrays:

• Always validate that collection parameters are not null before processing them
• For optional collections, consider:

  if (resolvers != null) {
    // process resolvers
  }
  

• Or enforce non-null values through constructor validation

Using these patterns consistently will reduce null-related bugs and improve code quality across the codebase.