What's the usual solution? Grab files from somewhere and statically include them in your source tree.
Result: trouble upgrades and license headhaches, especially if you took the good decision to release your code as Open Source.
We used to fall exactly in this uncomfortable trap at Apache Syncope, especially for the shining, eye-candy, AJAX-powered, web admin console, when I found WebJars, a great Open Source project with purpose of packaging client-side web libraries into JAR (Java Archive) files:
Now that SYNCOPE-443 has been fixed, Apache Syncope 1.2.0 will benefit from WebJars: nice work, guys!