public static KeyData createAesGcmKeyData(byte[] keyValue) throws Exception {
    AesGcmKey keyProto = AesGcmKey.newBuilder().setKeyValue(ByteString.copyFrom(keyValue)).build();
    return createKeyData(keyProto, AeadConfig.AES_GCM_TYPE_URL, KeyData.KeyMaterialType.SYMMETRIC);
  }
@return a {@code KeyData} containing a {@code AesGcmKey}.
java_src/src/main/java/com/google/crypto/tink/testing/TestUtil.java