[librest/wip/baedert/tests: 7/10] RestProxyCall: Document return value of _lookup_response_headers

[Timm Bäder <baedert src gnome org>]

commit 3b2a9a4acc0d2a67abe72c56e0d803dd1c75a817
Author: Timm Bäder <mail baedert org>
Date:   Thu Jul 21 22:42:26 2016 +0200

    RestProxyCall: Document return value of _lookup_response_headers

 rest/rest-proxy-call.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/rest/rest-proxy-call.c b/rest/rest-proxy-call.c
index 834470d..aac7806 100644
--- a/rest/rest-proxy-call.c
+++ b/rest/rest-proxy-call.c
@@ -1248,6 +1248,9 @@ rest_proxy_call_sync (RestProxyCall *call,
  *
  * Get the string value of the header @header or %NULL if that header is not
  * present or there are no headers.
+ *
+ * Returrns: (nullable): The string value of the header @header, or %NULL
+ *   if no header with that name exists.
  */
 const gchar *
 rest_proxy_call_lookup_response_header (RestProxyCall *call,
@@ -1256,6 +1259,7 @@ rest_proxy_call_lookup_response_header (RestProxyCall *call,
   RestProxyCallPrivate *priv = GET_PRIVATE (call);
 
   g_return_val_if_fail (REST_IS_PROXY_CALL (call), NULL);
+  g_return_val_if_fail (header != NULL);
 
   if (!priv->response_headers)
   {