code: public Callable<?> get(String id, Class<?> type) {
  
      Resolver callable = this.id2callableMap.get(id);
      if (callable == null) {
        callable = new Resolver(id, type);
        this.id2callableMap.put(id, callable);
      }
      return callable;
    }
docs: This method {@link com.sun.xml.bind.IDResolver#resolve(String, Class) resolves} the value with the given {@code id}
  .
  
  @param id is the {@link javax.xml.bind.annotation.XmlIDREF} of the requested object. This object should be
  {@link #put(String, Object) bound}. This may also happen after it has been requested.
  @param type is the expected type of the object.
  @return a {@link Callable} that {@link Callable#call() resolves} the requested value.