'Custom' => function ( &$data, &$metadata ) {
if ( isset( $metadata[ApiResult::META_TYPE] ) ) {
// We want to use non-BC for BCassoc to force outputting of _idx.
'Custom' => function ( &$data, &$metadata ) {
if ( isset( $metadata[ApiResult::META_TYPE] ) ) {
// We want to use non-BC for BCassoc to force outputting of _idx.