private static StringBuilder append(
      StringBuilder builder,
      List<? extends AnnotationMirror> annotations) {
    int i = 0;
    for (AnnotationMirror annotation : annotations) {
      if (i++ > 0) {
        // not the first annotation, so inserting space to separate
        builder.append(' ');
      }
      AnnotationMirrors.append(builder, annotation);
    }
    return builder;
  }
overridable stringify.
@param input the input
@param context the context
@return the string
generator/src/org/immutables/generator/TypeHierarchyCollector.java