Refactor common email sending utility

The main thrust of this is to create a common POJO that contains email content in a simple way, then have one class that converts that to an email and sends it. Any class that uses email should only have to deal with creating that POJO.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=237883643

java/google/registry/reporting/billing/BillingEmailUtils.java

@@ -20,23 +20,17 @@ import static java.nio.charset.StandardCharsets.UTF_8;
 import com.google.appengine.tools.cloudstorage.GcsFilename;
 import com.google.common.collect.ImmutableList;
 import com.google.common.io.CharStreams;
+import com.google.common.net.MediaType;
 import google.registry.config.RegistryConfig.Config;
 import google.registry.gcs.GcsUtils;
 import google.registry.reporting.billing.BillingModule.InvoiceDirectoryPrefix;
-import google.registry.util.Retrier;
+import google.registry.util.EmailMessage;
+import google.registry.util.EmailMessage.Attachment;
 import google.registry.util.SendEmailService;
-import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import javax.inject.Inject;
-import javax.mail.BodyPart;
-import javax.mail.Message;
-import javax.mail.Message.RecipientType;
-import javax.mail.MessagingException;
-import javax.mail.Multipart;
 import javax.mail.internet.InternetAddress;
-import javax.mail.internet.MimeBodyPart;
-import javax.mail.internet.MimeMultipart;
 import org.joda.time.YearMonth;
 
 /** Utility functions for sending emails involving monthly invoices. */
@@ -44,27 +38,25 @@ class BillingEmailUtils {
 
   private final SendEmailService emailService;
   private final YearMonth yearMonth;
-  private final String outgoingEmailAddress;
-  private final String alertRecipientAddress;
-  private final ImmutableList<String> invoiceEmailRecipients;
+  private final InternetAddress outgoingEmailAddress;
+  private final InternetAddress alertRecipientAddress;
+  private final ImmutableList<InternetAddress> invoiceEmailRecipients;
   private final String billingBucket;
   private final String invoiceFilePrefix;
   private final String invoiceDirectoryPrefix;
   private final GcsUtils gcsUtils;
-  private final Retrier retrier;
 
   @Inject
   BillingEmailUtils(
       SendEmailService emailService,
       YearMonth yearMonth,
-      @Config("gSuiteOutgoingEmailAddress") String outgoingEmailAddress,
-      @Config("alertRecipientEmailAddress") String alertRecipientAddress,
-      @Config("invoiceEmailRecipients") ImmutableList<String> invoiceEmailRecipients,
+      @Config("gSuiteOutgoingEmailAddress") InternetAddress outgoingEmailAddress,
+      @Config("alertRecipientEmailAddress") InternetAddress alertRecipientAddress,
+      @Config("invoiceEmailRecipients") ImmutableList<InternetAddress> invoiceEmailRecipients,
       @Config("billingBucket") String billingBucket,
       @Config("invoiceFilePrefix") String invoiceFilePrefix,
       @InvoiceDirectoryPrefix String invoiceDirectoryPrefix,
-      GcsUtils gcsUtils,
-      Retrier retrier) {
+      GcsUtils gcsUtils) {
     this.emailService = emailService;
     this.yearMonth = yearMonth;
     this.outgoingEmailAddress = outgoingEmailAddress;
@@ -74,50 +66,34 @@ class BillingEmailUtils {
     this.invoiceFilePrefix = invoiceFilePrefix;
     this.invoiceDirectoryPrefix = invoiceDirectoryPrefix;
     this.gcsUtils = gcsUtils;
-    this.retrier = retrier;
   }
 
   /** Sends an e-mail to all expected recipients with an attached overall invoice from GCS. */
   void emailOverallInvoice() {
     try {
-      retrier.callWithRetry(
-          () -> {
-            String invoiceFile =
-                String.format("%s-%s.csv", invoiceFilePrefix, yearMonth);
-            GcsFilename invoiceFilename =
-                new GcsFilename(billingBucket, invoiceDirectoryPrefix + invoiceFile);
-            try (InputStream in = gcsUtils.openInputStream(invoiceFilename)) {
-              Message msg = emailService.createMessage();
-              msg.setFrom(new InternetAddress(outgoingEmailAddress));
-              for (String recipient : invoiceEmailRecipients) {
-                msg.addRecipient(RecipientType.TO, new InternetAddress(recipient));
-              }
-              msg.setSubject(
-                  String.format("Domain Registry invoice data %s", yearMonth));
-              Multipart multipart = new MimeMultipart();
-              BodyPart textPart = new MimeBodyPart();
-              textPart.setText(
-                  String.format(
-                      "Attached is the %s invoice for the domain registry.", yearMonth));
-              multipart.addBodyPart(textPart);
-              BodyPart invoicePart = new MimeBodyPart();
-              String invoiceData = CharStreams.toString(new InputStreamReader(in, UTF_8));
-              invoicePart.setContent(invoiceData, "text/csv; charset=utf-8");
-              invoicePart.setFileName(invoiceFile);
-              multipart.addBodyPart(invoicePart);
-              msg.setContent(multipart);
-              msg.saveChanges();
-              emailService.sendMessage(msg);
-            }
-          },
-          IOException.class,
-          MessagingException.class);
+      String invoiceFile = String.format("%s-%s.csv", invoiceFilePrefix, yearMonth);
+      GcsFilename invoiceFilename =
+          new GcsFilename(billingBucket, invoiceDirectoryPrefix + invoiceFile);
+      try (InputStream in = gcsUtils.openInputStream(invoiceFilename)) {
+        emailService.sendEmail(
+            EmailMessage.newBuilder()
+                .setSubject(String.format("Domain Registry invoice data %s", yearMonth))
+                .setBody(
+                    String.format("Attached is the %s invoice for the domain registry.", yearMonth))
+                .setFrom(outgoingEmailAddress)
+                .setRecipients(invoiceEmailRecipients)
+                .setAttachment(
+                    Attachment.newBuilder()
+                        .setContent(CharStreams.toString(new InputStreamReader(in, UTF_8)))
+                        .setContentType(MediaType.CSV_UTF_8)
+                        .setFilename(invoiceFile)
+                        .build())
+                .build());
+      }
     } catch (Throwable e) {
       // Strip one layer, because callWithRetry wraps in a RuntimeException
       sendAlertEmail(
-          String.format(
-              "Emailing invoice failed due to %s",
-              getRootCause(e).getMessage()));
+          String.format("Emailing invoice failed due to %s", getRootCause(e).getMessage()));
       throw new RuntimeException("Emailing invoice failed", e);
     }
   }
@@ -125,17 +101,13 @@ class BillingEmailUtils {
   /** Sends an e-mail to the provided alert e-mail address indicating a billing failure. */
   void sendAlertEmail(String body) {
     try {
-      retrier.callWithRetry(
-          () -> {
-            Message msg = emailService.createMessage();
-            msg.setFrom(new InternetAddress(outgoingEmailAddress));
-            msg.addRecipient(RecipientType.TO, new InternetAddress(alertRecipientAddress));
-            msg.setSubject(String.format("Billing Pipeline Alert: %s", yearMonth));
-            msg.setText(body);
-            emailService.sendMessage(msg);
-            return null;
-          },
-          MessagingException.class);
+      emailService.sendEmail(
+          EmailMessage.newBuilder()
+              .setSubject(String.format("Billing Pipeline Alert: %s", yearMonth))
+              .setBody(body)
+              .addRecipient(alertRecipientAddress)
+              .setFrom(outgoingEmailAddress)
+              .build());
     } catch (Throwable e) {
       throw new RuntimeException("The alert e-mail system failed.", e);
     }