Remove unused AANull Gson adapters and imports

Commented-out code and unused imports related to AANull Gson adapters have been removed from AAChartView.kt and AANull.kt to clean up the codebase and improve maintainability.

Author: AAChartModel

charts/src/main/java/com/github/aachartmodel/aainfographics/aachartcreator/AAChartView.kt

@@ -51,9 +51,6 @@ import com.github.aachartmodel.aainfographics.aaoptionsmodel.AAPointEvents
 import com.github.aachartmodel.aainfographics.aaoptionsmodel.AASeries
 import com.github.aachartmodel.aainfographics.aatools.AAColor
 import com.github.aachartmodel.aainfographics.aatools.AAJSStringPurer
-//import com.github.aachartmodel.aainfographics.aatools.AANull
-//import com.github.aachartmodel.aainfographics.aatools.AANullAdapter
-//import com.github.aachartmodel.aainfographics.aatools.AANullObjectAdapter
 import com.github.aachartmodel.aainfographics.aatools.aa_toJSArray
 import com.google.gson.Gson
 import com.google.gson.GsonBuilder
@@ -130,12 +127,8 @@ class AAChartView : WebView {
 
     private var optionsJson: String? = null
 
-    // Centralized Gson configured to handle AANull and keep null fields
     private val aaGson: Gson by lazy {
         GsonBuilder()
-//            .registerTypeAdapter(String::class.java, AANullAdapter())
-//            .registerTypeAdapter(AANull::class.java, AANullObjectAdapter())
-//            .serializeNulls()
             .create()
     }
 

charts/src/main/java/com/github/aachartmodel/aainfographics/aatools/AANull.kt

@@ -1,50 +1,4 @@
 package com.github.aachartmodel.aainfographics.aatools
 
-import com.google.gson.TypeAdapter
-import com.google.gson.annotations.JsonAdapter
-import com.google.gson.stream.JsonReader
-import com.google.gson.stream.JsonToken
-import com.google.gson.stream.JsonWriter
-
-//// 实现 Javascript 中的 null 值的效果
-//@JsonAdapter(AANullObjectAdapter::class)
 class AANull {
 }
-//
-//// Adapter used for String properties: when the literal string "AANull" is encountered, output real JSON null
-//class AANullAdapter : TypeAdapter<String>() {
-//    override fun write(out: JsonWriter, value: String?) {
-//        if (value == "AANull") {
-//            out.nullValue() // 输出真正的 null
-//        } else {
-//            out.value(value)
-//        }
-//    }
-//
-//    override fun read(reader: JsonReader): String? {
-//        return if (reader.peek() == JsonToken.NULL) {
-//            reader.nextNull()
-//            null
-//        } else {
-//            val result = reader.nextString()
-//            if (result == "AANull") null else result
-//        }
-//    }
-//}
-//
-//// Adapter used for AANull object properties: serialize any AANull instance as JSON null
-//class AANullObjectAdapter : TypeAdapter<AANull>() {
-//    override fun write(out: JsonWriter, value: AANull?) {
-//        out.nullValue()
-//    }
-//
-//    override fun read(reader: JsonReader): AANull? {
-//        if (reader.peek() == JsonToken.NULL) {
-//            reader.nextNull()
-//        } else {
-//            // Consume any unexpected token to keep the stream consistent
-//            reader.skipValue()
-//        }
-//        return null
-//    }
-//}