So I have this regex written in Groovy, that gets all the FASTA files from a directory:

output = file(sample_dir).listFiles().findAll{ it.getName() =~ /${sample_name}.*\.f(?:ast)?[qa](?:\.gz)?/ }

Nextflow server complains about the slashy part, probably that is not supported, as described here . How am I supposed to write this Regex in a non slashy way?