docs: protected Set<String> facebookFieldNamesWithMultipleMappings(
        List<FieldWithAnnotation<Facebook>> fieldsWithAnnotation) {
      Map<String, Integer> facebookFieldsNamesWithOccurrenceCount = new HashMap<>();
      Set<String> facebookFieldNamesWithMultipleMappings = new HashSet<>();
  
      // Get a count of Facebook field name occurrences for each
      // @Facebook-annotated field
      for (FieldWithAnnotation<Facebook> fieldWithAnnotation : fieldsWithAnnotation) {
        String fieldName = getFacebookFieldName(fieldWithAnnotation);
        int occurrenceCount = facebookFieldsNamesWithOccurrenceCount.containsKey(fieldName)
            ? facebookFieldsNamesWithOccurrenceCount.get(fieldName)
            : 0;
        facebookFieldsNamesWithOccurrenceCount.put(fieldName, occurrenceCount + 1);
      }
  
      // Pull out only those field names with multiple mappings
      for (Entry<String, Integer> entry : facebookFieldsNamesWithOccurrenceCount.entrySet()) {
        if (entry.getValue() > 1) {
          facebookFieldNamesWithMultipleMappings.add(entry.getKey());
        }
      }
  
      return unmodifiableSet(facebookFieldNamesWithMultipleMappings);
    }