Add TLD identifier to premium terms filename and header

https://b.corp.google.com/issues/390053672

This makes it easier to identify what file you're looking at, at a
glance

Author: gbrodman

core/src/main/java/google/registry/export/ExportPremiumTermsAction.java

@@ -54,7 +54,8 @@ public class ExportPremiumTermsAction implements Runnable {
 
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();
   static final MediaType EXPORT_MIME_TYPE = MediaType.PLAIN_TEXT_UTF_8;
-  static final String PREMIUM_TERMS_FILENAME = "CONFIDENTIAL_premium_terms.txt";
+  static final String TLD_IDENTIFIER_FORMAT = "# TLD: %s";
+  static final String PREMIUM_TERMS_FILENAME_FORMAT = "CONFIDENTIAL_premium_terms_%s.txt";
 
   @Inject DriveConnection driveConnection;
 
@@ -127,7 +128,7 @@ private String exportPremiumTerms(Tld tld) {
     try {
       String fileId =
           driveConnection.createOrUpdateFile(
-              PREMIUM_TERMS_FILENAME,
+              String.format(PREMIUM_TERMS_FILENAME_FORMAT, tldStr),
               EXPORT_MIME_TYPE,
               tld.getDriveFolderId(),
               getFormattedPremiumTerms(tld).getBytes(UTF_8));
@@ -150,11 +151,9 @@ private String getFormattedPremiumTerms(Tld tld) {
             .map(PremiumEntry::toString)
             .collect(ImmutableSortedSet.toImmutableSortedSet(String::compareTo));
 
-    return Joiner.on("\n")
-        .appendTo(
-            new StringBuilder(),
-            Iterables.concat(ImmutableList.of(exportDisclaimer.trim()), premiumTerms))
-        .append("\n")
-        .toString();
+    String tldIdentifier = String.format(TLD_IDENTIFIER_FORMAT, tldStr);
+    Iterable<String> commentsAndTerms =
+        Iterables.concat(ImmutableList.of(exportDisclaimer.trim(), tldIdentifier), premiumTerms);
+    return Joiner.on("\n").join(commentsAndTerms) + "\n";
   }
 }

core/src/test/java/google/registry/export/ExportPremiumTermsActionTest.java

@@ -17,7 +17,6 @@
 import static com.google.common.net.MediaType.PLAIN_TEXT_UTF_8;
 import static com.google.common.truth.Truth.assertThat;
 import static google.registry.export.ExportPremiumTermsAction.EXPORT_MIME_TYPE;
-import static google.registry.export.ExportPremiumTermsAction.PREMIUM_TERMS_FILENAME;
 import static google.registry.testing.DatabaseHelper.createTld;
 import static google.registry.testing.DatabaseHelper.deleteTld;
 import static google.registry.testing.DatabaseHelper.persistResource;
@@ -52,11 +51,10 @@
 /** Unit tests for {@link ExportPremiumTermsAction}. */
 public class ExportPremiumTermsActionTest {
 
-  private static final String DISCLAIMER_WITH_NEWLINE = "# Premium Terms Export Disclaimer\n";
   private static final ImmutableList<String> PREMIUM_NAMES =
       ImmutableList.of("2048,USD 549", "0,USD 549");
   private static final String EXPECTED_FILE_CONTENT =
-      DISCLAIMER_WITH_NEWLINE + "0, 549.00\n" + "2048, 549.00\n";
+      "# Premium Terms Export Disclaimer\n# TLD: tld\n0, 549.00\n" + "2048, 549.00\n";
 
   @RegisterExtension
   final JpaIntegrationTestExtension jpa =
@@ -69,7 +67,7 @@ private void runAction(String tld) {
     ExportPremiumTermsAction action = new ExportPremiumTermsAction();
     action.response = response;
     action.driveConnection = driveConnection;
-    action.exportDisclaimer = DISCLAIMER_WITH_NEWLINE;
+    action.exportDisclaimer = "# Premium Terms Export Disclaimer\n";
     action.tldStr = tld;
     action.run();
   }
@@ -94,7 +92,7 @@ void test_exportPremiumTerms_success() throws IOException {
 
     verify(driveConnection)
         .createOrUpdateFile(
-            PREMIUM_TERMS_FILENAME,
+            "CONFIDENTIAL_premium_terms_tld.txt",
             EXPORT_MIME_TYPE,
             "folder_id",
             EXPECTED_FILE_CONTENT.getBytes(UTF_8));
@@ -157,7 +155,7 @@ void testExportPremiumTerms_failure_driveIdThrowsException() throws IOException
 
     verify(driveConnection)
         .createOrUpdateFile(
-            PREMIUM_TERMS_FILENAME,
+            "CONFIDENTIAL_premium_terms_tld.txt",
             EXPORT_MIME_TYPE,
             "bad_folder_id",
             EXPECTED_FILE_CONTENT.getBytes(UTF_8));