private HpkeParameters getDefaultValidParams() throws GeneralSecurityException {
    return HpkeParameters.builder()
        .setVariant(HpkeParameters.Variant.NO_PREFIX)
        .setKemId(HpkeParameters.KemId.DHKEM_X25519_HKDF_SHA256)
        .setKdfId(HpkeParameters.KdfId.HKDF_SHA256)
        .setAeadId(HpkeParameters.AeadId.AES_256_GCM)
        .build();
  }
Unit tests for {@link HpkeEncrypt} and {@link HpkeDecrypt}.
java_src/src/test/java/com/google/crypto/tink/hybrid/internal/HpkeEncryptDecryptTest.java