String[] existingApiResponseFields = { "api1", "api2" };
        queryFieldConfig.setApiResponseFields(existingApiResponseFields);

        String[] existingNotAnalyzedFields = { "not_analyzed1", "not_analyzed2" };
        queryFieldConfig.setNotAnalyzedFields(existingNotAnalyzedFields);

        // Initialize
        queryFieldConfig.init();

        // Verify that existing fields are not overwritten