Update fragment call in templates to use `~{}` syntax. First change file path to templates you want to affect.

thymeleaf_script.sh

#!/bin/sh

search_dir="/Users/alexgonzalez/Desktop/Code/form-flow/src/test/resources/templates"

# for each file in search directory and subdirectories, do the following
find "$search_dir" -type f -name "*.html" | while read file; do
    sed -n '
        /\(fragments.*\)"/ {
            s/\(fragments.*\)"/~{\1}"/g
            p
            s/.*//
            h
        }
        !/\(fragments.*\)"/ {
            H
            $!d
        }
        $ {
            p
        }
    ' "$file" > "${file}.tmp" && mv "${file}.tmp" "$file"
done