android 混淆后报如错 java.lang.ClassCastException

android 升级 gradle  混淆后报如错 java.lang.ClassCastException

Caused by: java.lang.ClassCastException
  at androidx.appcompat.app.ToolbarActionBar$$ExternalSyntheticThrowCCEIfNotNull0.m(:0)

原因： retrofit 混淆问题

解决： 将如下加入混淆配置

配置来源

https://github.com/square/retrofit/blob/dfdad425e9d1c47dbce335c9808c75c72ef912cc/retrofit/src/main/resources/META-INF/proguard/retrofit2.pro#L31

# Retrofit does reflection on generic parameters. InnerClasses is required to use Signature and
# EnclosingMethod is required to use InnerClasses.
-keepattributes Signature, InnerClasses, EnclosingMethod

# Retrofit does reflection on method and parameter annotations.
-keepattributes RuntimeVisibleAnnotations, RuntimeVisibleParameterAnnotations

# Keep annotation default values (e.g., retrofit2.http.Field.encoded).
-keepattributes AnnotationDefault

# Retain service method parameters when optimizing.
-keepclassmembers,allowshrinking,allowobfuscation interface * {
    @retrofit2.http.* <methods>;
}

# Ignore annotation used for build tooling.
-dontwarn org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement

# Ignore JSR 305 annotations for embedding nullability information.
-dontwarn javax.annotation.**

# Guarded by a NoClassDefFoundError try/catch and only used when on the classpath.
-dontwarn kotlin.Unit

# Top-level functions that can only be used by Kotlin.
-dontwarn retrofit2.KotlinExtensions
-dontwarn retrofit2.KotlinExtensions$*

# With R8 full mode, it sees no subtypes of Retrofit interfaces since they are created with a Proxy
# and replaces all potential values with null. Explicitly keeping the interfaces prevents this.
-if interface * { @retrofit2.http.* <methods>; }
-keep,allowobfuscation interface <1>

# Keep inherited services.
-if interface * { @retrofit2.http.* <methods>; }
-keep,allowobfuscation interface * extends <1>

# With R8 full mode generic signatures are stripped for classes that are not
# kept. Suspend functions are wrapped in continuations where the type argument
# is used.
-keep,allowobfuscation,allowshrinking class kotlin.coroutines.Continuation

# R8 full mode strips generic signatures from return types if not kept.
-if interface * { @retrofit2.http.* public *** *(...); }
-keep,allowoptimization,allowshrinking,allowobfuscation class <3>

# With R8 full mode generic signatures are stripped for classes that are not kept.
-keep,allowobfuscation,allowshrinking class retrofit2.Response