How to avoid reflection using enums

I recently asked a question about some code of mine where I used reflection and one who wanted to help me with this problem mentioned that I shouldn't use reflection like this and that there is a better way doing it.

So I have an Interface for searching in external Systems:

public interface ReferenceController {

  public Map<String, ReferenceElement> searchElements(String searchField, List<String> searchItems, SystemStage systemStage) throws Exception;

  public String getStateMapping(String value);

  public Boolean isAvailable(SystemStage systemStage) throws Exception;
}

And I have an ENUM where I declare which external systems I have and how their class is named which uses this interface. So if any other programmer want's to implement a new external system he has only to fill the interface and put two values in this ENUM and tada it should work.

So the part where I used the reflection was

public static void performSingleSearch(ReferenceSystem referenceSystem, String searchField, List<String> searchValues, SystemStage systemStage) throws Exception {

    if(!isAvailable(referenceSystem, systemStage)) return;
    Map<String, ReferenceElement> result = new HashMap<>();
    try {
        Class<?> classTemp = Class.forName(referenceSystem.getClassname());
        Method method = classTemp.getMethod("searchElements", String.class , List.class, SystemStage.class);
        result = (Map<String, ReferenceElement>) method.invoke(classTemp.newInstance(), searchField, searchValues, systemStage);
    } catch (Exception e) { 
        return;
    }
    if(result != null) orderResults(result, referenceSystem);
}

In the ENUM ther is a function getClassname, which answers with the fqcn.

So the other user here said there would be the possibility of implementing the interface into the enum and then I don't have to reflect. Could anyone tell me how, because I don't know and I don't know where or what to search. Thanks