Update OkHttp and R8 rule

Author: koji-1009

studyplus-android-sdk/build.gradle

@@ -7,8 +7,6 @@ android {
         minSdkVersion versions.minSdk
         targetSdkVersion versions.targetSdk
 
-        consumerProguardFiles 'lib-proguard-rules.txt'
-
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
@@ -47,7 +45,7 @@ dependencies {
     implementation "androidx.annotation:annotation:$versions.annotation"
     implementation "androidx.core:core-ktx:$versions.core_ktx"
 
-    def okhttp = "3.14.2"
+    def okhttp = "4.2.0"
     implementation "com.squareup.okhttp3:okhttp:$okhttp"
 
     testImplementation 'junit:junit:4.12'

studyplus-android-sdk/lib-proguard-rules.txt

@@ -4,19 +4,21 @@ import jp.studyplus.android.sdk.BuildConfig
 import kotlinx.coroutines.CompletableDeferred
 import kotlinx.coroutines.Deferred
 import okhttp3.*
+import okhttp3.MediaType.Companion.toMediaTypeOrNull
+import okhttp3.RequestBody.Companion.toRequestBody
 import org.json.JSONObject
 import java.io.IOException
 
 internal class ApiService(private val client: OkHttpClient) {
     fun post(auth: String, json: String): Deferred<Long?> {
         val body = createPostBody(json)
         val request = Request.Builder()
-                .header("Accept", HEADER_JSON)
-                .header("Content-type", HEADER_JSON)
-                .addHeader("Authorization", auth)
-                .url("$ENDPOINT/v1/study_records")
-                .post(body)
-                .build()
+            .header("Accept", HEADER_JSON)
+            .header("Content-type", HEADER_JSON)
+            .addHeader("Authorization", auth)
+            .url("$ENDPOINT/v1/study_records")
+            .post(body)
+            .build()
 
         return execute(client.newCall(request))
     }
@@ -27,10 +29,9 @@ internal class ApiService(private val client: OkHttpClient) {
     }
 }
 
-private val JSON_MEDIA_TYPE = MediaType.parse("application/json; charset=utf-8")
+private val JSON_MEDIA_TYPE = "application/json; charset=utf-8".toMediaTypeOrNull()
 
-internal fun createPostBody(json: String) =
-        RequestBody.create(JSON_MEDIA_TYPE, json)
+internal fun createPostBody(json: String) = json.toRequestBody(JSON_MEDIA_TYPE)
 
 internal fun execute(call: Call): Deferred<Long?> {
     val deferred = CompletableDeferred<Long?>()
@@ -51,7 +52,7 @@ internal fun execute(call: Call): Deferred<Long?> {
 
         override fun onResponse(call: Call, response: Response) {
             if (response.isSuccessful) {
-                val parsedJson = JSONObject(response.body()?.string() ?: EMPTY_JSON)
+                val parsedJson = JSONObject(response.body?.string() ?: EMPTY_JSON)
                 val recordId = parsedJson.optLong(RECORD_ID, INVALID_RECORD_ID)
 
                 if (recordId != INVALID_RECORD_ID) {