Remove unnecessary generic from JobKeyGenerator interface

[patrickwinti]

The JobKeyGenerator<T> interface currently uses a generic type parameter <T> to represent the source used to generate a job key. However, in practice, the implementations and usages of this interface rely on JobParameters as the source type.

Since the generic parameter is not providing meaningful flexibility and introduces unnecessary complexity (e.g., requiring casts or wildcard types in consumers), it would be cleaner to refactor the interface to:

public interface JobKeyGenerator {
    String generateKey(JobParameters source);
}