De-serialization for Java Map<custom class object, Boolean> using Jackson

I have a class-1 member variable => Map<(class-2) object, Boolean>. The jackson is not able to de-serialize the Map, and hence returning the Null object in an API.

I have tried making my own custom de-serializer but it's not working well for me.

Class-1

    private String contact;
    
    @JsonDeserialize(keyUsing = MyCustomDeserializer.class)
    private Map<class-2, Boolean> events;
    
    private String delivery;

Class-2

    private static final long serialVersionUID = 1L;
    
    Integer id;
    String age;
    String grp;

Custom Deserializer

public class MyCustomDeserializer extends KeyDeserializer {

     private Log log = LogFactory.getLog(getClass());

    @Override
    public Class-2 deserializeKey(String key, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        
        log.debug(key);  // not getting any print in logs
        return null;  // not sure about it
    }
}

Also, not sure about where to add this code and which class should be in this below code.

        final ObjectMapper objectMapper = new ObjectMapper();
        SimpleModule simpleModule = new SimpleModule();
        simpleModule.addKeyDeserializer(which class??, new MyCustomDeserializer());
        objectMapper.registerModule(simpleModule);