Speculative Generality.

There’s an unused class, method, field or parameter.

interface PaymentFactoryProvider {
  PaymentFactory factory(); // only one implementation exists
}
class CashProvider implements PaymentFactoryProvider {
  public PaymentFactory factory() { return new CashFactory(); }
}

Sometimes code is created “just in case” to support anticipated future features that never get implemented. As a result, code becomes hard to understand and support.

• Slimmer code.

• Easier support.