private CharSequence extractSourceCode() {
      CharSequence charSequence = consumer.asCharSequence();
      if (Strings.commonPrefix(charSequence, NO_IMPORTS).startsWith(NO_IMPORTS)) {
        return charSequence;
      }
      //return PostprocessingMachine.rewrite(charSequence);
      return ImportRewriter.rewrite(charSequence);
    }
Pragma-like comment indicator just at beginning of the source file used to disable import
post-processing.
generator/src/org/immutables/generator/Output.java