Grouping plugins for same filetypes

What is the best way to group plugins for same filetype?
I wanted to use this:
```
if index(['pm','perl','xs'], &filetype) > -1
Plug 'vim-perl/vim-perl'
Plug 'vim-scripts/perl-support.vim'
endif
```
But it does not work. I want to avoid use multiply keyword **for**:
```
Plug 'vim-perl/vim-perl', {'for',['perl','xs','pm']}
Plug 'vim-scripts/perl-support.vim', {'for',['perl','xs','pm']}
```
Of course xs and pm files have same filetype: perl. This is only example.

Best regards Piotr