[TSDB] Expose aggregate_metric_double fields as their own field type instead of double

x-pack/plugin/mapper-aggregate-metric/src/main/java/org/elasticsearch/xpack/aggregatemetric/mapper/AggregateDoubleMetricFieldMapper.java

@@ -298,11 +298,6 @@ private NumberFieldMapper.NumberFieldType delegateFieldType() {
             return delegateFieldType(defaultMetric);
         }
 
-        @Override
-        public String familyTypeName() {
-            return NumberFieldMapper.NumberType.DOUBLE.typeName();
-        }
-
         @Override
         public String typeName() {
             return CONTENT_TYPE;

x-pack/plugin/mapper-aggregate-metric/src/test/java/org/elasticsearch/xpack/aggregatemetric/mapper/AggregateDoubleMetricFieldMapperTests.java

@@ -522,7 +522,7 @@ public void testNoSubFieldsIterated() throws IOException {
     public void testFieldCaps() throws IOException {
         MapperService aggMetricMapperService = createMapperService(fieldMapping(this::minimalMapping));
         MappedFieldType fieldType = aggMetricMapperService.fieldType("field");
-        assertThat(fieldType.familyTypeName(), equalTo("double"));
+        assertThat(fieldType.familyTypeName(), equalTo("aggregate_metric_double"));
         assertTrue(fieldType.isSearchable());
         assertTrue(fieldType.isAggregatable());
     }

x-pack/plugin/src/yamlRestTest/resources/rest-api-spec/test/aggregate-metrics/110_field_caps.yml

@@ -72,6 +72,58 @@ setup:
                 type: double
                 time_series_metric: gauge
 
+  - do:
+      indices.create:
+        index: test_aggregate_metric
+        body:
+          mappings:
+            properties:
+              metric:
+                type: aggregate_metric_double
+                metrics: [ min, max, value_count ]
+                default_metric: max
+
+---
+aggregate_metric on standard index:
+  - skip:
+      version: " - 8.4.99"
+      reason: aggregate_metric_double field caps changed in 8.5.0
+
+  - do:
+      field_caps:
+        index: test_aggregate_metric
+        fields: [ metric ]
+
+  - match: { fields.metric.aggregate_metric_double.searchable: true }
+  - match: { fields.metric.aggregate_metric_double.aggregatable: true }
+  - is_false: fields.metric.aggregate_metric_double.indices
+
+---
+aggregate_metric on standard index conflict with double:
+  - skip:
+      version: " - 8.4.99"
+      reason: aggregate_metric_double field caps changed in 8.5.0
+
+  - do:
+      indices.create:
+        index: test_double
+        body:
+          mappings:
+            properties:
+              metric:
+                type: double
+
+  - do:
+      field_caps:
+        index: [test_double, test_aggregate_metric]
+        fields: [ metric ]
+
+  - match: { fields.metric.aggregate_metric_double.searchable: true }
+  - match: { fields.metric.aggregate_metric_double.aggregatable: true }
+  - match: { fields.metric.aggregate_metric_double.indices: [ test_aggregate_metric ] }
+  - match: { fields.metric.double.searchable: true }
+  - match: { fields.metric.double.aggregatable: true }
+  - match: { fields.metric.double.indices: [ test_double ] }
 
 ---
 # Test field_caps on a rollup index