private static HpkeParams getHpkeParams() {
    return HpkeParams.newBuilder()
        .setKem(HpkeKem.DHKEM_X25519_HKDF_SHA256)
        .setKdf(HpkeKdf.HKDF_SHA256)
        .setAead(HpkeAead.AES_128_GCM)
        .build();
  }
This test attempts to test the case where a user registers their own key type with
Registry.registerKeyManager() and then uses it.
java_src/src/test/java/com/google/crypto/tink/hybrid/KeyManagerIntegrationTest.java