Fix _source accepting an array of fields in _search. (#430)

Signed-off-by: dblock <[email protected]>

CHANGELOG.md

@@ -86,6 +86,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Fixed query DSL `match` that supports a field name and value ([#405](https://github.com/opensearch-project/opensearch-api-specification/pull/405)) 
 - Fixed `/_mapping` with `index` in query ([#385](https://github.com/opensearch-project/opensearch-api-specification/pull/385))
 - Fixed duplicate `/_nodes/{node_id}` path ([#416](https://github.com/opensearch-project/opensearch-api-specification/pull/416))
+- Fixed `_source` accepting an array of fields in `/_search` ([#430](https://github.com/opensearch-project/opensearch-api-specification/pull/430))
 
 ### Security
 

spec/schemas/_core.search.yaml

@@ -789,6 +789,9 @@ components:
       description: Defines how to fetch a source. Fetching can be disabled entirely, or the source can be filtered.
       oneOf:
         - type: boolean
+        - type: array
+          items:
+            $ref: '_common.yaml#/components/schemas/Field' 
         - $ref: '#/components/schemas/SourceFilter'
     SourceFilter:
       type: object

tests/_core/search/_source.yaml

@@ -0,0 +1,147 @@
+$schema: ../../../json_schemas/test_story.schema.yaml
+
+description: Test search endpoint (_source).
+prologues:
+  - path: /movies/_doc
+    method: POST
+    parameters:
+      refresh: true
+    request_body:
+      payload:
+        director: Bennett Miller
+        title: Moneyball
+        year: 2011
+    status: [201]
+epilogues:
+  - path: /movies
+    method: DELETE
+    status: [200, 404]
+chapters:
+  - synopsis: Search (_source=true).
+    path: /{index}/_search
+    parameters:
+      index: movies
+    method: POST
+    request_body:
+      payload:
+        _source: true
+        query:
+          match_all: {}
+    response:
+      status: 200
+      payload:
+        timed_out: false
+        hits:
+          total:
+            value: 1
+            relation: eq
+          max_score: 1
+          hits:
+            - _index: movies
+              _score: 1
+              _source:
+                director: Bennett Miller
+                title: Moneyball
+                year: 2011
+  - synopsis: Search (_source=false).
+    path: /{index}/_search
+    parameters:
+      index: movies
+    method: POST
+    request_body:
+      payload:
+        _source: false
+        query:
+          match_all: {}
+    response:
+      status: 200
+      payload:
+        timed_out: false
+        hits:
+          total:
+            value: 1
+            relation: eq
+          max_score: 1
+          hits:
+            - _index: movies
+              _score: 1
+  - synopsis: Search (_source=[fields]).
+    path: /{index}/_search
+    parameters:
+      index: movies
+    method: POST
+    request_body:
+      payload:
+        _source:
+          - director
+          - year
+        query:
+          match_all: {}
+    response:
+      status: 200
+      payload:
+        timed_out: false
+        hits:
+          total:
+            value: 1
+            relation: eq
+          max_score: 1
+          hits:
+            - _index: movies
+              _score: 1
+              _source:
+                director: Bennett Miller
+                year: 2011
+  - synopsis: Search (_source=filter).
+    path: /{index}/_search
+    parameters:
+      index: movies
+    method: POST
+    request_body:
+      payload:
+        _source:
+          includes: director
+          excludes: year
+        query:
+          match_all: {}
+    response:
+      status: 200
+      payload:
+        timed_out: false
+        hits:
+          total:
+            value: 1
+            relation: eq
+          max_score: 1
+          hits:
+            - _index: movies
+              _score: 1
+              _source:
+                director: Bennett Miller
+  - synopsis: Search (_source=filter with wildcards).
+    path: /{index}/_search
+    parameters:
+      index: movies
+    method: POST
+    request_body:
+      payload:
+        _source:
+          includes: '*'
+          excludes: year
+        query:
+          match_all: {}
+    response:
+      status: 200
+      payload:
+        timed_out: false
+        hits:
+          total:
+            value: 1
+            relation: eq
+          max_score: 1
+          hits:
+            - _index: movies
+              _score: 1
+              _source:
+                director: Bennett Miller
+                title: Moneyball