fix request creator to take an array of strings for the map rather th…

…an just a string

Sources/Apollo/RequestCreator.swift

@@ -55,13 +55,13 @@ public struct RequestCreator {
     let operationData = try serializationFormat.serialize(value: fields)
     formData.appendPart(data: operationData, name: "operations")
 
-    var map = [String: String]()
+    var map = [String: [String]]()
     if files.count == 1 {
       let firstFile = files.first!
-      map[firstFile.originalName] = "[variables.\(firstFile.fieldName)]"
+      map[firstFile.originalName] = ["variables.\(firstFile.fieldName)"]
     } else {
       for (index, file) in files.enumerated() {
-        map[file.originalName] = "[variables.\(file.fieldName).\(index)]"
+        map[file.originalName] = ["variables.\(file.fieldName).\(index)"]
       }
     }
 

Tests/ApolloTests/MultipartFormDataTests.swift

@@ -184,7 +184,7 @@ Content-Disposition: form-data; name="operations"
 --TEST.BOUNDARY
 Content-Disposition: form-data; name="map"
 
-{"a.txt":"[variables.upload]"}
+{"a.txt":["variables.upload"]}
 --TEST.BOUNDARY
 Content-Disposition: form-data; name="upload"; filename="a.txt"
 Content-Type: text/plain
@@ -200,7 +200,7 @@ Alpha file content.
 --TEST.BOUNDARY
 Content-Disposition: form-data; name="map"
 
-{"a.txt":"[variables.upload]"}
+{"a.txt":["variables.upload"]}
 --TEST.BOUNDARY
 Content-Disposition: form-data; name="upload"; filename="a.txt"
 Content-Type: text/plain
@@ -246,7 +246,7 @@ Content-Disposition: form-data; name="operations"
 --TEST.BOUNDARY
 Content-Disposition: form-data; name="map"
 
-{"a.txt":"[variables.uploads.0]","b.txt":"[variables.uploads.1]"}
+{"a.txt":["variables.uploads.0"],"b.txt":["variables.uploads.1"]}
 --TEST.BOUNDARY
 Content-Disposition: form-data; name="uploads"; filename="a.txt"
 Content-Type: text/plain