message: Remove the functions assertEnoughKeyMaterial and assertEnoughEncryptedKeyMaterial from the public API.
  Since they are taking as input protos which aren't in the public API, I do not expect anyone to call those.
diff: @@ -354,7 +354,7 @@ public final class KeysetHandle {
  *
  * @throws GeneralSecurityException
  */
  - public static void assertEnoughKeyMaterial(Keyset keyset) throws GeneralSecurityException {
  + private static void assertEnoughKeyMaterial(Keyset keyset) throws GeneralSecurityException {
  if (keyset == null || keyset.getKeyCount() <= 0) {
  throw new GeneralSecurityException("empty keyset");
  }
  @@ -365,7 +365,7 @@ public final class KeysetHandle {
  *
  * @throws GeneralSecurityException
  */
  - public static void assertEnoughEncryptedKeyMaterial(EncryptedKeyset keyset)
  + private static void assertEnoughEncryptedKeyMaterial(EncryptedKeyset keyset)
  throws GeneralSecurityException {
  if (keyset == null || keyset.getEncryptedKeyset().size() == 0) {
  throw new GeneralSecurityException("empty keyset");
  