How To Design - Interface Usage

I have a class as shown below. This class has a method addFilter with 2 parameters (type String and type Command1 )

public class Command1 {
public StringBuffer addFilter(String query, Command1 dataBase) {
//concrete implementation
return query;
}
}

I have another class Command2. Here I need a similar method. The only difference is in the type of parameters passed. (type String and type Command).

public class Command2 {
//TO DO:
public StringBuffer addFilter(String query, Command2 cmd) {
//concrete implementation
return query;
}
}

I have started by using Interface

public interface Helper {
public StringBuffer addFilter(String query, XXXXX parameter2);
}

I would like the classes Command1 and Command2 to implement the interface Helper and override it these two public classes.

However my problem is in dealing with the 2nd parameter. Am I right in my approach? How do I handle this issue?