code: static <I, O> CipherExecutor<I, O> getInstance() {
          if (INSTANCE == null) {
              synchronized (NoOpCipherExecutor.class) {
                  if (INSTANCE == null) {
                      INSTANCE = new NoOpCipherExecutor<>();
                  }
              }
          }
          return INSTANCE;
      }
docs: Gets instance.
  
  @return the instance