Add utility methods for copying time transition maps and filtering grace periods

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=130281141

java/google/registry/model/common/TimedTransitionProperty.java

@@ -125,6 +125,17 @@ public class TimedTransitionProperty<V, T extends TimedTransitionProperty.TimedT
         makeTransitionMap(valueMap, timedTransitionSubclass)));
   }
 
+  /**
+   * Returns a new immutable {@code TimedTransitionProperty} containing the same transitions as the
+   * current object, up to but not including the desired date. All transitions on or after that date
+   * will be deleted.
+   *
+   * @param asOfDate the date before which transitions should be retained
+   */
+  public TimedTransitionProperty<V, T> copyUntilJustBefore(DateTime asOfDate) {
+    return new TimedTransitionProperty<>(backingMap.headMap(asOfDate, false));
+  }
+
   /**
    * Returns a new mutable {@code TimedTransitionProperty} representing the given map of DateTime
    * to value, with transitions constructed using the given {@code TimedTransition} subclass.

java/google/registry/model/domain/DomainResource.java

@@ -217,6 +217,37 @@ public class DomainResource extends DomainBase implements ForeignKeyedEppResourc
     return ImmutableSet.copyOf(gracePeriodStatuses);
   }
 
+  /**
+   * Returns the Registry Grace Period expiration date for the specified type of grace period for
+   * this domain, or null if there is no grace period of the specified type.
+   */
+  public Optional<DateTime> getGracePeriodExpirationTime(GracePeriodStatus gracePeriodType) {
+    for (GracePeriod gracePeriod : getGracePeriods()) {
+      if (gracePeriod.getType() == gracePeriodType) {
+        return Optional.of(gracePeriod.getExpirationTime());
+      }
+    }
+    return Optional.absent();
+  }
+
+  /**
+   * Checks to see if the domain is in a particular type of grace period at the specified time. We
+   * only check the expiration time, because grace periods are always assumed to start at the
+   * beginning of time. This could be confusing if asOfDate is in the past. For instance, the Add
+   * Grace Period will appear to last from the beginning of time until 5 days after the domain is
+   * created.
+   */
+  public boolean doesAnyGracePeriodOfTypeExpireAfter(
+      GracePeriodStatus gracePeriodType, DateTime asOfDate) {
+    for (GracePeriod gracePeriod : getGracePeriods()) {
+      if ((gracePeriod.getType() == gracePeriodType)
+          && gracePeriod.getExpirationTime().isAfter(asOfDate)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
   /**
    * The logic in this method, which handles implicit server approval of transfers, very closely
    * parallels the logic in {@code DomainTransferApproveFlow} which handles explicit client