Update to Kotlin 1.5 (and associated deps) (#1339)

kotlin/codegen/build.gradle.kts

@@ -22,7 +22,7 @@ plugins {
   kotlin("jvm")
   kotlin("kapt")
   id("com.vanniktech.maven.publish")
-  id("com.github.johnrengelman.shadow") version "6.0.0"
+  id("com.github.johnrengelman.shadow") version "7.0.0"
 }
 
 tasks.withType<KotlinCompile>().configureEach {
@@ -102,6 +102,6 @@ val shadowJar = tasks.shadowJar.apply {
 }
 
 artifacts {
-  runtime(shadowJar)
+  runtimeOnly(shadowJar)
   archives(shadowJar)
 }

kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/api/DelegateKey.kt

@@ -31,6 +31,7 @@ import com.squareup.kotlinpoet.asClassName
 import com.squareup.kotlinpoet.asTypeName
 import com.squareup.moshi.JsonAdapter
 import com.squareup.moshi.Types
+import java.util.Locale
 
 /** A JsonAdapter that can be used to encode and decode a particular field. */
 internal data class DelegateKey(
@@ -50,7 +51,7 @@ internal data class DelegateKey(
       "At${it.typeName.rawType().simpleName}"
     }
     val adapterName = nameAllocator.newName(
-      "${type.toVariableName().decapitalize()}${qualifierNames}Adapter",
+      "${type.toVariableName().replaceFirstChar { it.lowercase(Locale.US) }}${qualifierNames}Adapter",
       this
     )