Aggregations: Fixed Histogram key_as_string bug

The key as string field in the response for the histogram aggregation will now only show if format is specified on the request.

Closes #6655

rest-api-spec/test/search.aggregation/10_histogram.yaml

@@ -0,0 +1,129 @@
+---
+"Basic test":
+  - do:
+      index:
+        index: test_1
+        type: test
+        id: 1
+        body: { "number" : 1 }
+
+  - do:
+      index:
+        index: test_1
+        type: test
+        id: 2
+        body: { "number" : 51 }
+
+  - do:
+      index:
+        index: test_1
+        type: test
+        id: 3
+        body: { "number" : 101 }
+      
+  - do:
+      index:
+        index: test_1
+        type: test
+        id: 4
+        body: { "number" : 151 }
+          
+  - do:
+      indices.refresh: {}
+    
+  - do:
+      search:
+        body: { "aggs" : { "histo" : { "histogram" : { "field" : "number", "interval" : 50 } } } }
+    
+  - match: { hits.total: 4 }
+  
+  - length: { aggregations.histo.buckets: 4 }
+  
+  - match: { aggregations.histo.buckets.0.key: 0 }
+  
+  - is_false: aggregations.histo.buckets.0.key_as_string
+  
+  - match: { aggregations.histo.buckets.0.doc_count: 1 }
+  
+  - match: { aggregations.histo.buckets.1.key: 50 }
+  
+  - is_false: aggregations.histo.buckets.1.key_as_string
+  
+  - match: { aggregations.histo.buckets.1.doc_count: 1 }
+  
+  - match: { aggregations.histo.buckets.2.key: 100 }
+  
+  - is_false: aggregations.histo.buckets.2.key_as_string
+  
+  - match: { aggregations.histo.buckets.2.doc_count: 1 }
+  
+  - match: { aggregations.histo.buckets.3.key: 150 }
+  
+  - is_false: aggregations.histo.buckets.3.key_as_string
+  
+  - match: { aggregations.histo.buckets.3.doc_count: 1 }
+  
+---
+"Format test":
+  - do:
+      index:
+        index: test_1
+        type: test
+        id: 1
+        body: { "number" : 1 }
+
+  - do:
+      index:
+        index: test_1
+        type: test
+        id: 2
+        body: { "number" : 51 }
+
+  - do:
+      index:
+        index: test_1
+        type: test
+        id: 3
+        body: { "number" : 101 }
+      
+  - do:
+      index:
+        index: test_1
+        type: test
+        id: 4
+        body: { "number" : 151 }
+          
+  - do:
+      indices.refresh: {}
+    
+  - do:
+      search:
+        body: { "aggs" : { "histo" : { "histogram" : { "field" : "number", "interval" : 50, "format" : "Value is ##0.0" } } } }
+    
+  - match: { hits.total: 4 }
+  
+  - length: { aggregations.histo.buckets: 4 }
+  
+  - match: { aggregations.histo.buckets.0.key: 0 }
+  
+  - match: { aggregations.histo.buckets.0.key_as_string: "Value is 0.0" }
+  
+  - match: { aggregations.histo.buckets.0.doc_count: 1 }
+  
+  - match: { aggregations.histo.buckets.1.key: 50 }
+  
+  - match: { aggregations.histo.buckets.1.key_as_string: "Value is 50.0" }
+  
+  - match: { aggregations.histo.buckets.1.doc_count: 1 }
+  
+  - match: { aggregations.histo.buckets.2.key: 100 }
+  
+  - match: { aggregations.histo.buckets.2.key_as_string: "Value is 100.0" }
+  
+  - match: { aggregations.histo.buckets.2.doc_count: 1 }
+  
+  - match: { aggregations.histo.buckets.3.key: 150 }
+  
+  - match: { aggregations.histo.buckets.3.key_as_string: "Value is 150.0" }
+  
+  - match: { aggregations.histo.buckets.3.doc_count: 1 }

src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalHistogram.java

@@ -120,7 +120,7 @@ public class InternalHistogram<B extends InternalHistogram.Bucket> extends Inter
         }
 
         void toXContent(XContentBuilder builder, Params params, boolean keyed, @Nullable ValueFormatter formatter) throws IOException {
-            if (formatter != null) {
+            if (formatter != null && formatter != ValueFormatter.RAW) {
                 Text keyTxt = new StringText(formatter.format(key));
                 if (keyed) {
                     builder.startObject(keyTxt.string());