telepathy-glib has the following callback type declared in an introspected header file:

typedef void (*TpConnectionRequestHandlesCb) (TpConnection *connection,
    TpHandleType handle_type,
    guint n_handles, const TpHandle *handles, const gchar * const *ids,
    const GError *error, gpointer user_data, GObject *weak_object);

Its documentation comment is declared in a (separate) introspected C file (though moving the comment into the same header file as the callback type definition doesn't seem to change anything):

/**
 * TpConnectionRequestHandlesCb:
 * @connection: the connection
 * @handle_type: the handle type that was passed to
 *  tp_connection_request_handles()
 * @n_handles: the number of IDs that were passed to
 *  tp_connection_request_handles() on success, or 0 on failure
 * @handles: (element-type uint) (array length=n_handles): the @n_handles
 *  handles corresponding to @ids, in the same order, or %NULL on failure
 * @ids: a copy of the array of @n_handles IDs that was passed to
 *  tp_connection_request_handles() on success, or %NULL on failure
 * @error: %NULL on success, or an error on failure
 * @user_data: the same arbitrary pointer that was passed to
 *  tp_connection_request_handles()
 * @weak_object: the same object that was passed to
 *  tp_connection_request_handles()
 *
 * Signature of the callback called when tp_connection_request_handles()
 * succeeds or fails.
 *
 * On success, the caller has one reference to each handle in @handles, which
 * may be released later with tp_connection_unref_handles(). If not
 * released, the handles will remain valid until @connection becomes invalid
 * (signalled by TpProxy::invalidated).
 *
 * For convenience, the handle type and IDs requested by the caller are
 * passed through to this callback, so the caller does not have to include
 * them in @user_data.
 */

The following GIR XML is generated, which seems to completely ignore both the documentation in the comment and the annotations:

    <callback name="ConnectionRequestHandlesCb" c:type="TelepathyGLibConnectionRequestHandlesCb">
      <return-value transfer-ownership="none">
        <type name="none" c:type="void"/>
      </return-value>
      <parameters>
        <parameter name="connection" transfer-ownership="none">
          <type name="Connection" c:type="TpConnection*"/>
        </parameter>
        <parameter name="handle_type" transfer-ownership="none">
          <type name="HandleType" c:type="TpHandleType"/>
        </parameter>
        <parameter name="n_handles" transfer-ownership="none">
          <type name="guint" c:type="guint"/>
        </parameter>
        <parameter name="handles" transfer-ownership="none">
          <type name="Handle" c:type="TpHandle*"/>
        </parameter>
        <parameter name="ids" transfer-ownership="none">
          <type name="utf8" c:type="gchar**"/>
        </parameter>
        <parameter name="error" transfer-ownership="none">
          <type name="GLib.Error" c:type="GError*"/>
        </parameter>
        <parameter name="user_data" transfer-ownership="none" closure="6">
          <type name="gpointer" c:type="gpointer"/>
        </parameter>
        <parameter name="weak_object" transfer-ownership="none">
          <type name="GObject.Object" c:type="GObject*"/>
        </parameter>
      </parameters>
    </callback>

Additionally, the c:type in the generated XML is wrong (it should have a "Tp" prefix, not a "TelepathyGLib" prefix).