code: public final <T1 extends SourceFile, T2 extends SourceFile> void init(
        List<T1> externs, List<T2> sources, CompilerOptions options) {
      JSModule module = new JSModule(JSModule.STRONG_MODULE_NAME);
      for (SourceFile source : sources) {
        module.add(new CompilerInput(source));
      }
  
      List<JSModule> modules = new ArrayList<>(1);
      modules.add(module);
      initModules(externs, modules, options);
      addFilesToSourceMap(sources);
    }
docs: Initializes the instance state needed for a compile job.