question: protected File unzipDistribution ( File dir , File zip ) { File exploded = new File ( dir , BOOTSTRAP_DISTRIBUTION + "-exploded" ) ; if ( exploded . exists ( ) ) { if ( forceBootstrapUpdate ( ) == false ) return exploded ; else delete ( exploded ) ; } try { final ZipFile zipFile = new ZipFile ( zip ) ; try { final Enumeration < ? extends ZipEntry > entries = zipFile . entries ( ) ; while ( entries . hasMoreElements ( ) ) { final ZipEntry ze = entries . nextElement ( ) ; final File file = new File ( exploded , ze . getName ( ) ) ; if ( ze . isDirectory ( ) ) { if ( FileUtil . mkdirs ( file ) == false ) throw new IllegalArgumentException ( "Cannot create dir: " + file ) ; } else { final FileOutputStream fos = new FileOutputStream ( file ) ; copyStream ( zipFile . getInputStream ( ze ) , fos ) ; } } } finally { zipFile . close ( ) ; } } catch ( IOException e ) { throw new IllegalArgumentException ( e ) ; } return exploded ; }
target:  Unzip bootstrap distrubution if not already present.