@Test
  public void testHChaCha20TestVectors() {
    for (HChaCha20TestVector test : hChaCha20TestVectors) {
      int[] output = ChaCha20Util.hChaCha20(test.key, test.in);
      assertThat(output).isEqualTo(test.out);
    }
  }
https://datatracker.ietf.org/doc/html/rfc7539#section-2.3.2
java_src/src/test/java/com/google/crypto/tink/aead/internal/ChaCha20UtilTest.java