code: public synchronized Set<Class<?>> scanPackage(String basePackage, ClassSelector selector) throws Exception {
          if (selector == null) {
              throw new NullPointerException("Selector cannot be null");
          }
          this.selector = selector;
          this.classes = new HashSet<Class<?>>();
          Set<Class<?>> aux;
          try {
              scanClasses0(basePackage);
              aux = this.classes;
          }
          finally {
              this.selector = null;
              this.classes = null;
          }
  
          return aux;
      }
docs: PUBLIC METHODS ------------------------------------------------------------------------------