code: public ConditionalVisibilityField<T> addConditionalVisibilityField(int viewResId,
                                                                         BooleanExtractor<T> extractor,
                                                                         int visibilityIfFalse) {
  
          ConditionalVisibilityField<T> field =
                  new ConditionalVisibilityField<T>(viewResId, extractor, visibilityIfFalse);
  
          mConditionalVisibilityFields.add(field);
  
          return field;
      }
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