code: private void addParams(TypeSpec.Builder parent, LocaleID id, NumberData data) {
      MethodSpec.Builder code = MethodSpec.constructorBuilder();
      code.addStatement("this.decimal = $S", data.decimal);
      code.addStatement("this.group = $S", data.group);
      code.addStatement("this.percent = $S", data.percent);
      code.addStatement("this.minus = $S", data.minus);
      code.addStatement("this.plus = $S", data.plus);
      code.addStatement("this.exponential = $S", data.exponential);
      code.addStatement("this.superscriptingExponent = $S", data.superscriptingExponent);
      code.addStatement("this.perMille = $S", data.perMille);
      code.addStatement("this.infinity = $S", data.infinity);
      code.addStatement("this.nan = $S", data.nan);
      code.addStatement("this.currencyDecimal = $S", data.currencyDecimal);
      code.addStatement("this.currencyGroup = $S", data.currencyGroup);
  
      TypeSpec.Builder params = TypeSpec.classBuilder("_Params")
          .superclass(NumberFormatterParams.class)
          .addModifiers(PRIVATE, STATIC)
          .addMethod(code.build());
  
      parent.addType(params.build());
    }
docs: Construct's the locale's number formatter params.