code: void store(Credential credential) {
      accessToken = credential.getAccessToken();
      refreshToken = credential.getRefreshToken();
      expirationTimeMillis = credential.getExpirationTimeMilliseconds();
    }
docs: Store information from the credential.
  
  @param credential credential whose {@link Credential#getAccessToken access token},
  {@link Credential#getRefreshToken refresh token}, and
  {@link Credential#getExpirationTimeMilliseconds expiration time} need to be stored