Mismatched NULL handling between GstPlayer/GstPlay and playbin2/3

Describe your issue

The uri argument for gst_player_set_uri() is marked as nullable:

/**
 * gst_player_set_uri:
 * @player: #GstPlayer instance
 * @uri: (nullable): next URI to play.
 *
 * Sets the next URI to play.
 */

Internally, the GstPlayer:uri property calls gst_play_set_uri(), which is also explicitly allowing a NULL value for the uri argument:

/**
 * gst_play_set_uri:
 * @play: #GstPlay instance
 * @uri: (nullable): next URI to play.
 *
 * Sets the next URI to play.
 * Since: 1.20
 */

GstPlay:uri will eventually set the uri property on either the playbin2 or the playbin3 elements, which do not support a NULL URI:

  if (uri == NULL) {
    g_warning ("cannot set NULL uri");
    return;
  }

Expected Behavior

No warning when calling gst_player_set_uri (player, NULL).

Observed Behavior

The following warning:

** (amberol:2): WARNING **: 16:34:51.870: cannot set NULL uri

Setup

• Operating System: Fedora Silverblue
• Device: Computer
• GStreamer Version: 1.18, but verified to commit 6d2f57b6