Avoid casting to generate SimplifiedIntervalList (#678)

CHANGELOG.md

@@ -9,7 +9,10 @@ pull request if there was one.
 
 ### Changed:
 
-
+- [Avoid casting to generate SimplifiedIntervalList](https://github.com/yahoo/fili/pull/677)
+    * Some downstream projects generated partial intervals as `ArrayList`, which cannot be cased to
+      `SimplifiedIntervalList` in places like `getVolatileIntervalsWithDefault`. The result is a casting exception which
+      crashes downstream applications. Casting is replaced with a explicit `SimplifiedIntervalList` object creation.
 
 ### Deprecated:
 

fili-core/src/main/java/com/yahoo/bard/webservice/web/handlers/VolatileDataRequestHandler.java

@@ -13,7 +13,10 @@
 import com.yahoo.bard.webservice.web.responseprocessors.ResponseContext;
 import com.yahoo.bard.webservice.web.responseprocessors.ResponseProcessor;
 
+import org.joda.time.Interval;
+
 import java.io.Serializable;
+import java.util.Collection;
 import java.util.Map;
 
 import javax.validation.constraints.NotNull;
@@ -85,9 +88,11 @@ public boolean handleRequest(
      * @return the volatile intervals from the request or an empty list
      */
     public static SimplifiedIntervalList getVolatileIntervalsWithDefault(Map<String, Serializable> context) {
-        return (SimplifiedIntervalList) context.computeIfAbsent(
-                VOLATILE_INTERVALS_CONTEXT_KEY.getName(),
-                (ignored) -> new SimplifiedIntervalList()
+        return new SimplifiedIntervalList(
+                (Collection<Interval>) context.computeIfAbsent(
+                        VOLATILE_INTERVALS_CONTEXT_KEY.getName(),
+                        (ignored) -> new SimplifiedIntervalList()
+                )
         );
     }
 }