fix: Change ScheduleJobPayload.jobStartTime from Instant to String

src/main/kotlin/org/opensearch/commons/alerting/model/ScheduleJobPayload.kt

@@ -13,24 +13,27 @@ import org.opensearch.core.xcontent.ToXContentObject
 import org.opensearch.core.xcontent.XContentBuilder
 import org.opensearch.core.xcontent.XContentParser
 import org.opensearch.core.xcontent.XContentParserUtils
-import java.time.Instant
 
 /**
  * Represents the payload for an externally scheduled monitor job.
  *
  * Written to the schedule target (e.g. SQS) by the monitor CRUD path,
  * and parsed back by the job poller at execution time.
+ *
+ * [jobStartTime] is a String to support both scheduler placeholders
+ * (e.g. "<aws.scheduler.scheduled-time>") on the producer side and
+ * actual ISO-8601 timestamps on the consumer side.
  */
 data class ScheduleJobPayload(
     val monitorId: String,
-    val jobStartTime: Instant,
+    val jobStartTime: String,
     val monitorConfig: String
 ) : ToXContentObject {
 
     override fun toXContent(builder: XContentBuilder, params: ToXContent.Params): XContentBuilder {
         builder.startObject()
         builder.field(MONITOR_ID_FIELD, monitorId)
-        builder.field(JOB_START_TIME_FIELD, jobStartTime.toString())
+        builder.field(JOB_START_TIME_FIELD, jobStartTime)
         builder.field(MONITOR_CONFIG_FIELD, monitorConfig)
         builder.endObject()
         return builder
@@ -56,7 +59,7 @@ data class ScheduleJobPayload(
 
         fun parse(xcp: XContentParser): ScheduleJobPayload {
             var monitorId: String? = null
-            var jobStartTime: Instant? = null
+            var jobStartTime: String? = null
             var monitorConfig: String? = null
 
             XContentParserUtils.ensureExpectedToken(
@@ -69,7 +72,7 @@ data class ScheduleJobPayload(
                 xcp.nextToken()
                 when (fieldName) {
                     MONITOR_ID_FIELD -> monitorId = xcp.text()
-                    JOB_START_TIME_FIELD -> jobStartTime = Instant.parse(xcp.text())
+                    JOB_START_TIME_FIELD -> jobStartTime = xcp.text()
                     MONITOR_CONFIG_FIELD -> monitorConfig = xcp.text()
                     else -> xcp.skipChildren()
                 }

src/test/kotlin/org/opensearch/commons/alerting/model/ScheduleJobPayloadTests.kt

@@ -11,7 +11,6 @@ import org.opensearch.commons.alerting.parser
 import org.opensearch.commons.alerting.randomQueryLevelMonitor
 import org.opensearch.commons.alerting.xContentRegistry
 import org.opensearch.core.xcontent.ToXContent
-import java.time.Instant
 
 class ScheduleJobPayloadTests {
 
@@ -26,7 +25,7 @@ class ScheduleJobPayloadTests {
         val monitor = randomQueryLevelMonitor().copy(id = "mon-123")
         val payload = ScheduleJobPayload(
             monitorId = monitor.id,
-            jobStartTime = Instant.parse("2026-04-23T10:00:00Z"),
+            jobStartTime = "2026-04-23T10:00:00Z",
             monitorConfig = serializeMonitor(monitor)
         )
 
@@ -36,16 +35,33 @@ class ScheduleJobPayloadTests {
 
         val parsed = ScheduleJobPayload.parse(parser(json))
         assertEquals("mon-123", parsed.monitorId)
-        assertEquals(Instant.parse("2026-04-23T10:00:00Z"), parsed.jobStartTime)
+        assertEquals("2026-04-23T10:00:00Z", parsed.jobStartTime)
         assertEquals(payload.monitorConfig, parsed.monitorConfig)
     }
 
+    @Test
+    fun `round-trip with EB placeholder as jobStartTime`() {
+        val monitor = randomQueryLevelMonitor().copy(id = "mon-eb")
+        val payload = ScheduleJobPayload(
+            monitorId = monitor.id,
+            jobStartTime = "<aws.scheduler.scheduled-time>",
+            monitorConfig = serializeMonitor(monitor)
+        )
+
+        val builder = org.opensearch.common.xcontent.XContentFactory.jsonBuilder()
+        payload.toXContent(builder, ToXContent.EMPTY_PARAMS)
+        val json = builder.toString()
+
+        val parsed = ScheduleJobPayload.parse(parser(json))
+        assertEquals("<aws.scheduler.scheduled-time>", parsed.jobStartTime)
+    }
+
     @Test
     fun `toMonitor preserves id and fields`() {
         val monitor = randomQueryLevelMonitor().copy(id = "mon-456")
         val payload = ScheduleJobPayload(
             monitorId = monitor.id,
-            jobStartTime = Instant.now(),
+            jobStartTime = "2026-04-23T10:00:00Z",
             monitorConfig = serializeMonitor(monitor)
         )
 
@@ -63,7 +79,7 @@ class ScheduleJobPayloadTests {
         )
         val payload = ScheduleJobPayload(
             monitorId = monitor.id,
-            jobStartTime = Instant.now(),
+            jobStartTime = "2026-04-23T10:00:00Z",
             monitorConfig = serializeMonitor(monitor)
         )
 
@@ -84,4 +100,15 @@ class ScheduleJobPayloadTests {
             ScheduleJobPayload.parse(parser(json))
         }
     }
+
+    @Test
+    fun `parse throws on missing jobStartTime`() {
+        val monitor = randomQueryLevelMonitor()
+        val json = "{\"monitorId\":\"mon-123\"," +
+            "\"monitorConfig\":\"${serializeMonitor(monitor).replace("\"", "\\\"")}\"}"
+
+        org.junit.jupiter.api.assertThrows<IllegalArgumentException> {
+            ScheduleJobPayload.parse(parser(json))
+        }
+    }
 }