allow non-negative window delay

src/main/java/com/amazon/opendistroforelasticsearch/ad/model/IntervalTimeConfiguration.java

@@ -40,8 +40,8 @@ public class IntervalTimeConfiguration extends TimeConfiguration {
      * @param unit     time unit
      */
     public IntervalTimeConfiguration(long interval, ChronoUnit unit) {
-        if (interval <= 0) {
-            throw new IllegalArgumentException(String.format(Locale.ROOT, "Interval %s should be positive", interval));
+        if (interval < 0) {
+            throw new IllegalArgumentException(String.format(Locale.ROOT, "Interval %s should be non-negative", interval));
         }
         if (!SUPPORTED_UNITS.contains(unit)) {
             throw new IllegalArgumentException(String.format(Locale.ROOT, "Timezone %s is not supported", unit));

src/main/java/com/amazon/opendistroforelasticsearch/ad/settings/AnomalyDetectorSettings.java

@@ -51,9 +51,9 @@ private AnomalyDetectorSettings() {}
         );
 
     public static final Setting<TimeValue> DETECTION_WINDOW_DELAY = Setting
-        .positiveTimeSetting(
+        .timeSetting(
             "ml.anomaly_detectors.detection_window_delay",
-            TimeValue.timeValueSeconds(30),
+            TimeValue.timeValueMinutes(0),
             Setting.Property.NodeScope,
             Setting.Property.Dynamic
         );

src/test/java/com/amazon/opendistroforelasticsearch/ad/model/IntervalTimeConfigurationTests.java

@@ -54,8 +54,8 @@ public void testWrongInterval() throws Exception {
         TestHelpers
             .assertFailWith(
                 IllegalArgumentException.class,
-                "should be positive",
-                () -> new IntervalTimeConfiguration(randomLongBetween(-100, 0), ChronoUnit.MINUTES)
+                "should be non-negative",
+                () -> new IntervalTimeConfiguration(randomLongBetween(-100, -1), ChronoUnit.MINUTES)
             );
     }