docs: public StartDocumentAnalysisRequest withFeatureTypes(FeatureType... featureTypes) {
          java.util.ArrayList<String> featureTypesCopy = new java.util.ArrayList<String>(featureTypes.length);
          for (FeatureType value : featureTypes) {
              featureTypesCopy.add(value.toString());
          }
          if (getFeatureTypes() == null) {
              setFeatureTypes(featureTypesCopy);
          } else {
              getFeatureTypes().addAll(featureTypesCopy);
          }
          return this;
      }