message: Use "auto" for type returned by Struct fields.
diff: @@ -35,7 +35,6 @@ using ::crypto::tink::CleartextKeysetHandle;
  using ::crypto::tink::KeysetHandle;
  using ::crypto::tink::test::IsOk;
  using ::google::crypto::tink::KeyTemplate;
  -using ::proto2::Map;
  using ::testing::Eq;
  using ::testing::IsEmpty;
  using ::testing::ElementsAre;
  @@ -84,8 +83,7 @@ TEST_F(JwtImplMacTest, MacComputeVerifySuccess) {
  raw_jwt->mutable_not_before()->set_nanos(123000000);
  raw_jwt->mutable_issued_at()->set_seconds(23456);
  raw_jwt->mutable_expiration()->set_seconds(34567);
  - Map<std::string, JwtClaimValue>* custom_claims =
  - raw_jwt->mutable_custom_claims();
  + auto custom_claims = raw_jwt->mutable_custom_claims();
  (*custom_claims)["null_claim"].set_null_value(
  tink_testing_api::NullValue::NULL_VALUE);
  (*custom_claims)["bool_claim"].set_bool_value(true);
  @@ -219,8 +217,7 @@ TEST_F(JwtImplSignatureTest, SignVerifySuccess) {
  raw_jwt->mutable_not_before()->set_seconds(12345);
  raw_jwt->mutable_issued_at()->set_seconds(23456);
  raw_jwt->mutable_expiration()->set_seconds(34567);
  - Map<std::string, JwtClaimValue>* custom_claims =
  - raw_jwt->mutable_custom_claims();
  + auto custom_claims = raw_jwt->mutable_custom_claims();
  (*custom_claims)["null_claim"].set_null_value(
  tink_testing_api::NullValue::NULL_VALUE);
  (*custom_claims)["bool_claim"].set_bool_value(true);
  