docs: private byte[] getObservation(boolean done) {
          byte[] obs = envState.obs;
          if (obs == null && !done) {
              try {
                  cond.await(COND_WAIT_SECONDS, TimeUnit.SECONDS);
              } catch (InterruptedException ie) {
              }
              obs = envState.obs;
          }
          if (obs == null) {
              obs = new byte[0];
          }
          return obs;
      }