Some suggestions

src/main/kotlin/org/koitharu/kotatsu/parsers/site/vi/CuuTruyenParser.kt

@@ -19,9 +19,9 @@ import java.util.*
 import java.util.zip.Inflater
 
 @MangaSourceParser("CUUTRUYEN", "CuuTruyen", "vi")
-internal class CuuTruyenParser(context: MangaLoaderContext) : PagedMangaParser(context, MangaParserSource.CUUTRUYEN, 20) {
+internal class CuuTruyenParser(context: MangaLoaderContext) : PagedMangaParser(context, MangaParserSource.CUUTRUYEN, 20), Interceptor {
 
-    override val configKeyDomain = ConfigKey.Domain("cuutruyen.net", "nettrom.com", "hetcuutruyen.net", "cuutruyent9sv7.xyz")
+    override val configKeyDomain = ConfigKey.Domain("cuutruyen.net")
 
     override val availableSortOrders: Set<SortOrder> = EnumSet.of(
         SortOrder.UPDATED,
@@ -79,10 +79,10 @@ internal class CuuTruyenParser(context: MangaLoaderContext) : PagedMangaParser(c
                 altTitle = null,
                 coverUrl = jo.getString("cover_url"),
                 largeCoverUrl = jo.getString("cover_mobile_url"),
-                author = jo.optString("author_name", ""),
+                author = jo.getStringOrNull("author_name"),
                 tags = emptySet(),
                 state = null,
-                description = "",
+                description = null,
                 isNsfw = false,
                 source = source,
                 rating = RATING_UNKNOWN,
@@ -128,7 +128,6 @@ internal class CuuTruyenParser(context: MangaLoaderContext) : PagedMangaParser(c
         }
     }
 
-    private inner class CuuTruyenImageInterceptor : Interceptor {
     override fun intercept(chain: Interceptor.Chain): Response {
         val request = chain.request()
         val response = chain.proceed(request)
@@ -175,7 +174,6 @@ internal class CuuTruyenParser(context: MangaLoaderContext) : PagedMangaParser(c
         }
         return outputStream.toByteArray()
     }
-    }
 
     private fun parseChapterDate(dateString: String): Long {
         return SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'", Locale.US).parse(dateString)?.time ?: 0L