code: def _extract_jar(self, coordinate, jar_path):
      
      with open(jar_path, 'rb') as f:
        sha = sha1(f.read()).hexdigest()
        outdir = os.path.join(self.workdir, 'extracted', sha)
      if not os.path.exists(outdir):
        ZIP.extract(jar_path, outdir)
        self.context.log.debug('Extracting jar {jar} at {jar_path}.'
                               .format(jar=coordinate, jar_path=jar_path))
      else:
        self.context.log.debug('Jar {jar} already extracted at {jar_path}.'
                               .format(jar=coordinate, jar_path=jar_path))
      return outdir
docs: Extracts the jar to a subfolder of workdir/extracted and returns the path to it.