message: Emphasizes Mac.java interface is for multi-time MACs
  ORIGINAL_AUTHOR=Erhan Nergiz
  GitOrigin-RevId:
diff: @@ -19,9 +19,10 @@ package com.google.crypto.tink;
  import java.security.GeneralSecurityException;
  /**
  - * Interface for MACs (Message Authentication Codes).
  - * This interface should be used for authentication only, and not for other purposes
  - * (for example, it should not be used to generate pseudorandom bytes).
  + * Interface for multi-time MACs (Message Authentication Codes).
  + * This interface should be used for multi-time authentication only, and not for other purposes
  + * (for example, it should not be used to generate pseudorandom bytes or one-time MACs like
  + * Poly1305).
  */
  public interface Mac {
  /**
  