Support time_zone on composite's date_histogram

We've been parsing the `time_zone` parameter on `date_hitogram` for a
while but it hasn't *done* anything. This wires it up.

Closes elastic#45199
Inspired by elastic#45200

rest-api-spec/src/main/resources/rest-api-spec/test/search.aggregation/230_composite.yml

@@ -782,3 +782,68 @@ setup:
   - length: { aggregations.test.buckets: 1 }
   - match: { aggregations.test.buckets.0.key.f: "192.168.0.1" }
   - match: { aggregations.test.buckets.0.doc_count: 1 }
+
+---
+"date_histogram with time_zone":
+  - do:
+      index:
+        index:   test
+        id:      7
+        body:    { "date": "2017-10-22T01:00:00" }
+        refresh: true
+  - do:
+      search:
+        index: test
+        body:
+          aggregations:
+            test:
+              composite:
+                sources: [
+                {
+                  "date": {
+                    "date_histogram": {
+                      "field": "date",
+                      "calendar_interval": "1d",
+                      "time_zone": "-02:00",
+                      "format": "iso8601" # Format makes the comparisons a little more obvious
+                    }
+                  }
+                }
+              ]
+
+  - match: { hits.total.value: 7 }
+  - match: { hits.total.relation: eq }
+  - length: { aggregations.test.buckets: 2 }
+  - match: { aggregations.test.buckets.0.key.date: "2017-10-20T00:00:00.000-02:00" }
+  - match: { aggregations.test.buckets.0.doc_count: 1 }
+  - match: { aggregations.test.buckets.1.key.date: "2017-10-21T00:00:00.000-02:00" }
+  - match: { aggregations.test.buckets.1.doc_count: 2 }
+
+  - do:
+      search:
+        index: test
+        body:
+          aggregations:
+            test:
+              composite:
+                after: {
+                  date: "2017-10-20"
+                }
+                sources: [
+                {
+                  "date": {
+                    "date_histogram": {
+                      "field": "date",
+                      "calendar_interval": "1d",
+                      "time_zone": "-02:00",
+                      "format": "iso8601" # Format makes the comparisons a little more obvious
+                    }
+                  }
+                }
+            ]
+
+  - match: { hits.total.value: 7 }
+  - match: { hits.total.relation: eq }
+  - length: { aggregations.test.buckets: 1 }
+  - match: { aggregations.test.buckets.0.key.date: "2017-10-21T00:00:00.000-02:00" }
+  - match: { aggregations.test.buckets.0.doc_count: 2 }

server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/CompositeValuesSourceBuilder.java

@@ -27,11 +27,12 @@
 import org.elasticsearch.index.query.QueryShardContext;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.search.aggregations.support.ValueType;
-import org.elasticsearch.search.aggregations.support.ValuesSourceConfig;
 import org.elasticsearch.search.aggregations.support.ValuesSource;
+import org.elasticsearch.search.aggregations.support.ValuesSourceConfig;
 import org.elasticsearch.search.sort.SortOrder;
 
 import java.io.IOException;
+import java.time.ZoneId;
 import java.util.Objects;
 
 /**
@@ -276,7 +277,15 @@ protected abstract CompositeValuesSourceConfig innerBuild(QueryShardContext quer
 
     public final CompositeValuesSourceConfig build(QueryShardContext queryShardContext) throws IOException {
         ValuesSourceConfig<?> config = ValuesSourceConfig.resolve(queryShardContext,
-            valueType, field, script, null,null, format);
+            valueType, field, script, null, timeZone(), format);
         return innerBuild(queryShardContext, config);
     }
+
+    /**
+     * The time zone for this value source. Default implementation returns {@code null}
+     * because most value source types don't support time zone.
+     */
+    protected ZoneId timeZone() {
+        return null;
+    }
 }

server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/DateHistogramValuesSourceBuilder.java

@@ -228,6 +228,7 @@ public DateHistogramValuesSourceBuilder timeZone(ZoneId timeZone) {
     /**
      * Gets the time zone to use for this aggregation
      */
+    @Override
     public ZoneId timeZone() {
         return timeZone;
     }