code: public void addClassToId(final Class<?> clazz, final String id) {
          Assert.notNull(clazz, "Class cannot be null");
          Assert.hasText(id, "Alias (id) cannot be null or contain only whitespaces");
  
          if (classToId.containsKey(clazz)) {
              throw new IllegalArgumentException("Class " + clazz + " has already defined alias (id) " + classToId.get(clazz)
                      + " cannot set another alias " + id);
          }
  
          if (idToClass.containsKey(id)) {
              throw new IllegalArgumentException("Alias (id) " + id + " is used by another class " + idToClass.get(id)
                      + " and cannot be used by " + clazz);
          }
  
          classToId.put(clazz, id);
          idToClass.put(id, clazz);
      }
docs: Adds single mapping: class <-> alias (id).
  
  @param clazz
  @param id