question: protected static List < String > expandArgFiles ( final List < File > files ) { final List < String > content = new ArrayList < String > ( ) ; for ( final File file : files ) { try { content . addAll ( PluginUtil . readFile ( file ) ) ; } catch ( final IOException exc ) { throw new RuntimeException ( "Could not open file: " + file . getAbsolutePath ( ) , exc ) ; } } return content ; }
target:  Return all the lines in all the files.