Iterate over list of methods and take the first non null response

I have three functions. Input and output parameters of all three functions are same.

Let's say

public void String function1(String abc, String xyz);
public void String function2(String abc, String xyz);
public void String function3(String abc, String xyz);

I have a caller function which is implemented like

public void String callerFunction(String abc, String xyz) {
     String output = function1(String abc, String xyz);
     if(output == null) { 
          output = function2(String abc, String xyz);
     } 
     
     if(output == null) { 
          output = function3(String abc, String xyz);
     } 
     return output;
}

While this code works, what's the best way to write this kind of logic, i may want to add a new function4 also in the future.

One way that comes in my mind is

public interface functionInterface {
      public String fetchValue(String abc, String xyz);
} 

public class function1Class {
      public String fetchValue(String abc, String xyz) {
         // return some string.
      }
} 

public class function2Class {
      public String fetchValue(String abc, String xyz) {
         // return some string.
      }
} 

public class function3Class {
      public String fetchValue(String abc, String xyz) {
         // return some string.
      }
}


public void String callerFunction(String abc, String xyz) {
     List<functionInterface> flist = new Arraylist<>();
     functionInterface f1 = new function1Class();
     functionInterface f2 = new function1Class();
     functionInterface f3 = new function1Class();
     flist.add(f1);
     flist.add(f2);
     flist.add(f3);
     
     String output = null;
     for(functionInterface f : flist) { 
         output = f.fetchValue(abc, xyz);
         if(f.fetchValue(abc, xyz) != null) {
            return output;
         }
     }
     return output;
}

• Is this over engineering ?
• Is there a better way to handle this use case ?