code: protected List<FaicliFailureErrorPart> toErrors(ApiFailureResource resource, Map<String, List<String>> propertyMessageMap) {
          final List<FaicliFailureErrorPart> partList = propertyMessageMap.entrySet().stream().flatMap(entry -> {
              return toFailureErrorPart(resource, entry.getKey(), entry.getValue()).stream();
          }).collect(Collectors.toList());
          return new ArrayList<FaicliFailureErrorPart>(partList); // mutable for additional errors
      }
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