code: public static Binder binder(Object module) {
          if (module instanceof AbstractModule) {
              try {
                  Method method = AbstractModule.class.getDeclaredMethod("binder");
                  if (!method.isAccessible()) {
                      method.setAccessible(true);
                  }
                  return (Binder) method.invoke(module);
              } catch (Exception e) {
                  throw new RuntimeException(e);
              }
          } else {
              throw new IllegalArgumentException("Module must be an instance of AbstractModule");
          }
      }
docs: Get the binder from an AbstractModule.