code: public void setClassToId(final Map<Class<?>, String> classToId) {
  
          Map<String, Class<?>> reverseMap = new HashMap<String, Class<?>>();
          for (Map.Entry<Class<?>, String> entry : classToId.entrySet()) {
              Assert.notNull(entry.getKey(), "Class cannot be null: " + entry);
              Assert.hasText(entry.getValue(), "Alias (id) cannot be null or contain only whitespaces" + entry);
  
              if (reverseMap.put(entry.getValue(), entry.getKey()) != null) {
                  throw new IllegalArgumentException("Two or more classes with the same alias (id): " + entry.getValue());
              }
          }
  
          this.classToId = classToId;
          this.idToClass = reverseMap;
      }
docs: Registers mappings between classes and aliases (ids).
  
  @param classToId