upgrade rxjava3

Author: hangga

core-kotlin-modules/core-kotlin-collections-6/pom.xml

@@ -15,10 +15,12 @@
 
     <dependencies>
         <dependency>
-            <groupId>io.reactivex.rxjava2</groupId>
+            <groupId>io.reactivex.rxjava3</groupId>
             <artifactId>rxkotlin</artifactId>
-            <version>${rxkotlin.version}</version>
+            <version>3.0.1</version>
+            <scope>runtime</scope>
         </dependency>
+
     </dependencies>
 
     <properties>

core-kotlin-modules/core-kotlin-collections-6/src/test/kotlin/com/baeldung/parallelOperationsCollections/ParallelOperationCollectionsUnitTest.kt

@@ -1,8 +1,8 @@
 package com.baeldung.parallelOperationsCollections
 
-import io.reactivex.Observable
-import io.reactivex.rxkotlin.toObservable
-import io.reactivex.schedulers.Schedulers
+import io.reactivex.rxjava3.core.Observable
+import io.reactivex.rxjava3.kotlin.toObservable
+import io.reactivex.rxjava3.schedulers.Schedulers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.async
 import kotlinx.coroutines.awaitAll