chore(docs): put kafka version in gradle.props

Author: cottand

build.gradle.kts

@@ -64,6 +64,7 @@ subprojects {
         }
     }
 
+    val kafkaVersion: String by project
     tasks.withType<DokkaTaskPartial>().configureEach {
         if (project.name != "docs") dokkaSourceSets {
             named("main") {
@@ -76,7 +77,7 @@ subprojects {
                     ))
                 }
                 externalDocumentationLink(
-                    url = URL("https://javadoc.io/doc/org.apache.kafka/kafka-clients/2.8.0/")
+                    url = URL("https://javadoc.io/doc/org.apache.kafka/kafka-clients/$kafkaVersion/")
                 )
                 externalDocumentationLink(
                     url = URL("https://kotlin.github.io/kotlinx.coroutines/")

core/build.gradle.kts

@@ -5,6 +5,7 @@ plugins {
 }
 
 dependencies {
-    api("org.apache.kafka:kafka_2.12:2.8.0")
+    val kafkaVersion: String by project
+    api("org.apache.kafka:kafka_2.12:$kafkaVersion")
     api("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.0")
 }

gradle.properties

@@ -6,3 +6,4 @@ version=0.0.1
 
 serializationLibVersion=1.2.1
 jacocoVersion=0.8.7
+kafkaVersion=2.8.0