Use Interface Instead of Concrete Type

It changes eligible declarations or references from a concrete class to an interface that the class implements. The goal is to reduce coupling while preserving the program's behavior.

Depending on an interface makes code easier to test and allows another implementation to be substituted later. For example, code can accept a `PaymentGateway` interface instead of being tied directly to one concrete gateway class.

The operation is intended to preserve behavior while changing the declared type where the interface provides the needed members. The result still needs compilation and tests because not every concrete-only method or property may be available through the interface.

Support depends on the JetBrains IDE and language plugin because the refactoring requires language-aware type analysis. It is available only when the selected concrete class has a suitable interface and the affected declarations are eligible.