11.2.2.9.2. @Transformable keys

@Transformable(transformer = CustomTransformer.class)
public class CustomKey {
   ...
}

public class CustomTransformer implements Transformer {
   @Override
   public Object fromString(String s) {
      ...
      return new CustomKey(...);
   }

   @Override
   public String toString(Object customType) {
      CustomKey ck = (CustomKey) customType;
      return ...
   }
}

org.infinispan.query.SearchManager.registerKeyTransformer(Class<?>, Class<? extends Transformer>)