Fix child first classloader

[tachimanga]

The original ChildFirstURLClassLoader did not work as expected. It first loads classes using the SystemClassLoader. Unlike Android's system ClassLoader, which only loads core classes (java., android.), the JVM's one also loads classes from the CLASSPATH, meaning if a class exists both in the extension and the host, it will be loaded by the host's class loader. (NOT child-first)

The new implementation is based on Flink’s ChildFirstClassLoader, which adopts an allowlist approach. Core JRE classes are loaded by the parent class loader first(like Android's SystemClassLoader), then the child class loader attempts to load them. If the child fails to load a class, it falls back to the parent, effectively achieving child-first class loading.

[tachimanga]

These are the names of classes loaded by the Android systemclassloader. Printed via

try {
    c = systemClassLoader.loadClass(name)
    println("[ext]loaded by sys:$name")
} catch (_: ClassNotFoundException) {}

[ext]loaded by sys:java.lang.CharSequence
[ext]loaded by sys:java.lang.Object
[ext]loaded by sys:java.io.Serializable
[ext]loaded by sys:java.lang.Enum
[ext]loaded by sys:java.util.concurrent.TimeUnit
[ext]loaded by sys:java.util.List
[ext]loaded by sys:java.lang.String
[ext]loaded by sys:java.lang.StringBuilder
[ext]loaded by sys:java.lang.UnsupportedOperationException
[ext]loaded by sys:java.lang.Iterable
[ext]loaded by sys:java.util.Collection
[ext]loaded by sys:java.lang.Boolean
[ext]loaded by sys:java.util.ArrayList
[ext]loaded by sys:java.util.Iterator
[ext]loaded by sys:android.util.Base64
[ext]loaded by sys:java.nio.charset.Charset
[ext]loaded by sys:java.lang.Integer
[ext]loaded by sys:android.net.Uri
[ext]loaded by sys:java.lang.Exception
[ext]loaded by sys:java.lang.Number
[ext]loaded by sys:java.util.regex.Pattern
[ext]loaded by sys:java.util.Set
[ext]loaded by sys:java.io.ObjectInputStream
[ext]loaded by sys:java.io.InvalidObjectException
[ext]loaded by sys:java.util.regex.Matcher
[ext]loaded by sys:java.lang.IndexOutOfBoundsException
[ext]loaded by sys:java.util.EnumSet
[ext]loaded by sys:java.util.Collections
[ext]loaded by sys:java.lang.Double
[ext]loaded by sys:java.lang.Float
[ext]loaded by sys:java.lang.IllegalStateException
[ext]loaded by sys:java.lang.Throwable
[ext]loaded by sys:java.lang.ClassNotFoundException
[ext]loaded by sys:java.lang.Class
[ext]loaded by sys:java.lang.NullPointerException
[ext]loaded by sys:java.lang.Thread
[ext]loaded by sys:java.lang.StackTraceElement
[ext]loaded by sys:java.util.Arrays
[ext]loaded by sys:java.lang.AssertionError
[ext]loaded by sys:java.lang.IllegalArgumentException
[ext]loaded by sys:java.lang.RuntimeException
[ext]loaded by sys:java.lang.Error
[ext]loaded by sys:java.util.RandomAccess
[ext]loaded by sys:java.util.ListIterator
[ext]loaded by sys:java.lang.reflect.Type

These are the names of classes loaded by the JVM systemclassloader. Printed via

try {
    c = systemClassLoader.loadClass(name)
    println("[ext]loadClass sys: $name")
} catch (_: ClassNotFoundException) {}

[ext]loadClass sys: okhttp3.Response
[ext]loadClass sys: okhttp3.Request
[ext]loadClass sys: kotlin.Lazy
[ext]loadClass sys: uy.kohesive.injekt.InjektKt
[ext]loadClass sys: uy.kohesive.injekt.api.InjektFactory
[ext]loadClass sys: uy.kohesive.injekt.api.FullTypeReference
[ext]loadClass by ext: eu.kanade.tachiyomi.extension.es.leercapitulo.LeerCapitulo$special$$inlined$injectLazy$1$1
[ext]loadClass sys: kotlinx.serialization.json.Json
[ext]loadClass sys: uy.kohesive.injekt.api.TypeReference
[ext]loadClass sys: okhttp3.ResponseBody
[ext]loadClass sys: kotlinx.serialization.internal.ArrayListSerializer
[ext]loadClass by ext: eu.kanade.tachiyomi.extension.es.leercapitulo.LeerCapitulo$MangaDto
[ext]loadClass by ext: eu.kanade.tachiyomi.extension.es.leercapitulo.LeerCapitulo$MangaDto$Companion
[ext]loadClass sys: kotlinx.serialization.internal.GeneratedSerializer
[ext]loadClass by ext: eu.kanade.tachiyomi.extension.es.leercapitulo.LeerCapitulo$MangaDto$$serializer
[ext]loadClass sys: kotlinx.serialization.UnknownFieldException
[ext]loadClass sys: kotlinx.serialization.internal.PluginGeneratedSerialDescriptor
[ext]loadClass sys: kotlinx.serialization.descriptors.SerialDescriptor
[ext]loadClass sys: kotlinx.serialization.KSerializer
[ext]loadClass sys: kotlinx.serialization.DeserializationStrategy
[ext]loadClass sys: kotlinx.serialization.encoding.Decoder
[ext]loadClass sys: kotlinx.serialization.encoding.CompositeDecoder
[ext]loadClass by ext: kotlinx.serialization.internal.GeneratedSerializer$_CC
[ext]loadClass sys: kotlinx.serialization.internal.PluginHelperInterfacesKt
[ext]loadClass sys: kotlinx.serialization.internal.StringSerializer
[ext]loadClass sys: java.lang.Iterable
[ext]loadClass sys: kotlin.collections.CollectionsKt
[ext]loadClass sys: java.util.Iterator
[ext]loadClass sys: eu.kanade.tachiyomi.source.model.MangasPage

As you can see, Android's SystemClassLoader only loads Java or Android classes, while the JVM's SystemClassLoader not only loads Java classes but also loads classes from the classpath.