[[.stringr_pattern method not defined

[mkoohafkan]

Method [.stringr_pattern is defined, but [[.stringr_pattern is not:

ex = coll(c("foo", "bar"))
ex[1]
#> [1] "foo"
#> attr(,"options")
#> attr(,"options")$locale
#> [1] "en"
#> 
#> attr(,"options")$strength
#> [1] 3
#> 
#> attr(,"class")
#> [1] "stringr_coll"    "stringr_pattern" "character"   
class(ex[1])
#> [1] "stringr_coll"    "stringr_pattern" "character" 

ex[[1]]
#> [1] "foo"
class(ex[[1]])
#> [1] "character"

Is this by design?