VOL-1691 Fix openolt adapter getting stuck while registartion with core

Change-Id: Ide8131f325bc15f1b909e14d7af6ee9bcd6b3b5b
diff --git a/vendor/golang.org/x/net/http2/server.go b/vendor/golang.org/x/net/http2/server.go
index 8f17019..57334dc 100644
--- a/vendor/golang.org/x/net/http2/server.go
+++ b/vendor/golang.org/x/net/http2/server.go
@@ -273,7 +273,20 @@
 		if testHookOnConn != nil {
 			testHookOnConn()
 		}
+		// The TLSNextProto interface predates contexts, so
+		// the net/http package passes down its per-connection
+		// base context via an exported but unadvertised
+		// method on the Handler. This is for internal
+		// net/http<=>http2 use only.
+		var ctx context.Context
+		type baseContexter interface {
+			BaseContext() context.Context
+		}
+		if bc, ok := h.(baseContexter); ok {
+			ctx = bc.BaseContext()
+		}
 		conf.ServeConn(c, &ServeConnOpts{
+			Context:    ctx,
 			Handler:    h,
 			BaseConfig: hs,
 		})
@@ -284,6 +297,10 @@
 
 // ServeConnOpts are options for the Server.ServeConn method.
 type ServeConnOpts struct {
+	// Context is the base context to use.
+	// If nil, context.Background is used.
+	Context context.Context
+
 	// BaseConfig optionally sets the base configuration
 	// for values. If nil, defaults are used.
 	BaseConfig *http.Server
@@ -294,6 +311,13 @@
 	Handler http.Handler
 }
 
+func (o *ServeConnOpts) context() context.Context {
+	if o.Context != nil {
+		return o.Context
+	}
+	return context.Background()
+}
+
 func (o *ServeConnOpts) baseConfig() *http.Server {
 	if o != nil && o.BaseConfig != nil {
 		return o.BaseConfig
@@ -439,7 +463,7 @@
 }
 
 func serverConnBaseContext(c net.Conn, opts *ServeConnOpts) (ctx context.Context, cancel func()) {
-	ctx, cancel = context.WithCancel(context.Background())
+	ctx, cancel = context.WithCancel(opts.context())
 	ctx = context.WithValue(ctx, http.LocalAddrContextKey, c.LocalAddr())
 	if hs := opts.baseConfig(); hs != nil {
 		ctx = context.WithValue(ctx, http.ServerContextKey, hs)
@@ -2307,7 +2331,16 @@
 
 func (cw chunkWriter) Write(p []byte) (n int, err error) { return cw.rws.writeChunk(p) }
 
-func (rws *responseWriterState) hasTrailers() bool { return len(rws.trailers) != 0 }
+func (rws *responseWriterState) hasTrailers() bool { return len(rws.trailers) > 0 }
+
+func (rws *responseWriterState) hasNonemptyTrailers() bool {
+	for _, trailer := range rws.trailers {
+		if _, ok := rws.handlerHeader[trailer]; ok {
+			return true
+		}
+	}
+	return false
+}
 
 // declareTrailer is called for each Trailer header when the
 // response header is written. It notes that a header will need to be
@@ -2407,7 +2440,10 @@
 		rws.promoteUndeclaredTrailers()
 	}
 
-	endStream := rws.handlerDone && !rws.hasTrailers()
+	// only send trailers if they have actually been defined by the
+	// server handler.
+	hasNonemptyTrailers := rws.hasNonemptyTrailers()
+	endStream := rws.handlerDone && !hasNonemptyTrailers
 	if len(p) > 0 || endStream {
 		// only send a 0 byte DATA frame if we're ending the stream.
 		if err := rws.conn.writeDataFromHandler(rws.stream, p, endStream); err != nil {
@@ -2416,7 +2452,7 @@
 		}
 	}
 
-	if rws.handlerDone && rws.hasTrailers() {
+	if rws.handlerDone && hasNonemptyTrailers {
 		err = rws.conn.writeHeaders(rws.stream, &writeResHeaders{
 			streamID:  rws.stream.id,
 			h:         rws.handlerHeader,