@BeforeClass
  public static void setUpClass() throws Exception {
    AeadConfig.register();
    Registry.registerKeyManager(new MyCustomKeyManager(), /* newKeyAllowed= */ true);
  }
A custom implementation of {@link com.google.crypto.tink.KeyManager} for AES GCM 128.

<p>It only implements the methods of the KeyManager interface that are needed.
java_src/src/test/java/com/google/crypto/tink/custom/CustomAeadKeyManagerTest.java