code: @Override
      public StandardJavaFileManager getStandardFileManager(
              DiagnosticListener<? super JavaFileObject> diagnosticListener,
              Locale locale,
              Charset charset) {
          Context context = new Context();
          context.put(Locale.class, locale);
          if (diagnosticListener != null)
              context.put(DiagnosticListener.class, diagnosticListener);
          PrintWriter pw = (charset == null)
                  ? new PrintWriter(System.err, true)
                  : new PrintWriter(new OutputStreamWriter(System.err, charset), true);
          context.put(Log.outKey, pw);
          return new JavacFileManager(context, true, charset);
      }
docs: TODO: used shared static method in JavacFileManager