I'd prefer that we copy and append to a file rather than store everything in memory. This is a perfect candidate for an OOM error.

Incidentally we have code in the extractor to do this already:

https://github.com/webjars/webjars-locator/blob/master/src/main/java/org/webjars/WebJarExtractor.java#L374

...perhaps we can lift that utility out of the extractor and make it available to the locator.