Upgrade to Kotlin 1.4.0

Closes gh-25617

build.gradle

@@ -1,6 +1,6 @@
 plugins {
 	id 'io.spring.dependency-management' version '1.0.9.RELEASE' apply false
-	id 'org.jetbrains.kotlin.jvm' version '1.4.0-rc' apply false
+	id 'org.jetbrains.kotlin.jvm' version '1.4.0' apply false
 	id 'org.jetbrains.dokka' version '0.10.1' apply false
 	id 'org.asciidoctor.jvm.convert' version '2.4.0'
 	id 'io.spring.nohttp' version '0.0.5.RELEASE'
@@ -29,8 +29,8 @@ configure(allprojects) { project ->
 			mavenBom "io.r2dbc:r2dbc-bom:Arabba-SR5"
 			mavenBom "io.rsocket:rsocket-bom:1.1.0-M1"
 			mavenBom "org.eclipse.jetty:jetty-bom:9.4.31.v20200723"
-			mavenBom "org.jetbrains.kotlin:kotlin-bom:1.4.0-rc"
-			mavenBom "org.jetbrains.kotlinx:kotlinx-coroutines-bom:1.3.8-1.4.0-rc"
+			mavenBom "org.jetbrains.kotlin:kotlin-bom:1.4.0"
+			mavenBom "org.jetbrains.kotlinx:kotlinx-coroutines-bom:1.3.9"
 			mavenBom "org.junit:junit-bom:5.6.2"
 		}
 		dependencies {