MODEXPW-651: Always format email context createdAt with millisecond precision

src/main/java/org/folio/dew/batch/acquisitions/mapper/OrderEmailContextMapper.java

@@ -32,7 +32,8 @@
 
 import java.math.BigDecimal;
 import java.time.Instant;
-import java.time.temporal.ChronoUnit;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeFormatterBuilder;
 import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
@@ -45,6 +46,8 @@
 @Log4j2
 public class OrderEmailContextMapper {
 
+  private static final DateTimeFormatter CREATED_AT_FORMATTER = new DateTimeFormatterBuilder().appendInstant(3).toFormatter();
+
   private final IdentifierTypeService identifierTypeService;
   private final ContributorNameTypeService contributorNameTypeService;
   private final ConfigurationService configurationService;
@@ -60,12 +63,16 @@ public OrderEmailContext buildContext(List<CompositePurchaseOrder> orders) {
           .toList()))
       .toList();
     return OrderEmailContext.builder()
-      .createdAt(Instant.now().truncatedTo(ChronoUnit.MILLIS).toString())
+      .createdAt(formatCreatedAt(Instant.now()))
       .organization(mapOrganization(orders))
       .orders(orderWrappers)
       .build();
   }
 
+  static String formatCreatedAt(Instant instant) {
+    return CREATED_AT_FORMATTER.format(instant);
+  }
+
   private OrganizationContext mapOrganization(List<CompositePurchaseOrder> orders) {
     return orders.stream()
       .map(CompositePurchaseOrder::getVendor)

src/test/java/org/folio/dew/batch/acquisitions/mapper/OrderEmailContextMapperTest.java

@@ -20,6 +20,7 @@
 import org.mockito.junit.jupiter.MockitoExtension;
 
 import java.io.IOException;
+import java.time.Instant;
 import java.util.List;
 import java.util.UUID;
 
@@ -176,6 +177,11 @@ void buildContext_setsCreatedAt() {
     assertThat(ctx.getCreatedAt()).matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}\\.\\d{3}Z");
   }
 
+  @Test
+  void formatCreatedAt_wholeSecond_keepsMilliseconds() {
+    assertThat(OrderEmailContextMapper.formatCreatedAt(Instant.parse("2026-08-12T10:15:30Z"))).isEqualTo("2026-08-12T10:15:30.000Z");
+  }
+
   @Test
   void buildContext_mapsOrganizationFields() throws IOException {
     var org = new Organization();