/**
* gst_pad_query_caps:
* @pad: a #GstPad to get the capabilities of.
- * @filter: suggested #GstCaps.
+ * @filter: (allow-none): suggested #GstCaps, or NULL
*
* Gets the capabilities this pad can produce or consume.
* Note that this method doesn't necessarily return the caps set by
/**
* gst_pad_peer_query_caps:
* @pad: a #GstPad to get the capabilities of.
- * @filter: a #GstCaps filter.
+ * @filter: (allow-none): a #GstCaps filter, or NULL.
*
* Gets the capabilities of the peer connected to this pad. Similar to
* gst_pad_query_caps().