http: Add ability to merge slashes (#7621)

Signed-off-by: Ruslan Nigmatullin <elessar@dropbox.com>

Mirrored from https://github.com/envoyproxy/envoy @ deccb6e215b2fc0df42481f373c6992024e184f9

envoy/config/filter/network/http_connection_manager/v2/http_connection_manager.proto

@@ -25,7 +25,7 @@ import "gogoproto/gogo.proto";
 // [#protodoc-title: HTTP connection manager]
 // HTTP connection manager :ref:`configuration overview <config_http_conn_man>`.
 
-// [#comment:next free field: 33]
+// [#comment:next free field: 34]
 message HttpConnectionManager {
   enum CodecType {
     option (gogoproto.goproto_enum_prefix) = false;
@@ -424,6 +424,13 @@ message HttpConnectionManager {
   // Note that Envoy does not perform
   // `case normalization <https://tools.ietf.org/html/rfc3986#section-6.2.2.1>`
   google.protobuf.BoolValue normalize_path = 30;
+
+  // Determines if adjacent slashes in the path are merged into one before any processing of
+  // requests by HTTP filters or routing. This affects the upstream *:path* header as well. Without
+  // setting this option, incoming requests with path `//dir///file` will not match against route
+  // with `prefix` match set to `/dir`. Defaults to `false`. Note that slash merging is not part of
+  // `HTTP spec <https://tools.ietf.org/html/rfc3986>` and is provided for convenience.
+  bool merge_slashes = 33;
 }
 
 message Rds {