code: public void setMappedClass(Class<T> mappedClass) {
          if (this.mappedClass == null) {
              initialize(mappedClass);
          }
          else {
              if (!this.mappedClass.equals(mappedClass)) {
                  throw new InvalidDataAccessApiUsageException("The mapped class can not be reassigned to map to " +
                          mappedClass + " since it is already providing mapping for " + this.mappedClass);
              }
          }
      }
docs: Set the class that each row should be mapped to.