All requests use Content-Type of application/json

Elasticsearch disabled Content-Type negotiation with 5.3.0. We now
always pass Content-Type: application/json by default.

See #511

clear_scroll.go

@@ -7,7 +7,6 @@ package elastic
 import (
 	"fmt"
 	"net/url"
-	"strings"
 
 	"golang.org/x/net/context"
 )
@@ -82,7 +81,9 @@ func (s *ClearScrollService) Do(ctx context.Context) (*ClearScrollResponse, erro
 	}
 
 	// Setup HTTP request body
-	body := strings.Join(s.scrollId, ",")
+	body := map[string][]string{
+		"scroll_id": s.scrollId,
+	}
 
 	// Get HTTP response
 	res, err := s.client.PerformRequest(ctx, "DELETE", path, params, body)

client.go

@@ -23,7 +23,7 @@ import (
 
 const (
 	// Version is the current version of Elastic.
-	Version = "5.0.34"
+	Version = "5.0.35"
 
 	// DefaultURL is the default endpoint of Elasticsearch on the local machine.
 	// It is used e.g. when initializing a new Client without a specific URL.

request.go

@@ -26,6 +26,7 @@ func NewRequest(method, url string) (*Request, error) {
 	}
 	req.Header.Add("User-Agent", "elastic/"+Version+" ("+runtime.GOOS+"-"+runtime.GOARCH+")")
 	req.Header.Add("Accept", "application/json")
+	req.Header.Set("Content-Type", "application/json")
 	return (*Request)(req), nil
 }