$params['index'] = (list) A comma-separated list of index names
$params['ignore_unavailable'] = (boolean) Whether specified concrete indices should be ignored when unavailable (missing or closed)
$params['allow_no_indices'] = (boolean) Whether to ignore if a wildcard indices expression resolves into no concrete indices. (This includes _all
string or when no indices have been specified)
$params['expand_wildcards'] = (enum) Whether to expand wildcard expression to concrete indices that are open, closed or both. (Options = open,closed,none,all) (Default = open)