Fix pom scope for Scala projects (mongodb#1531)

Required the `api` dependency method from the `java-library` plugin.
Now the scope is `compile` (api) instead of `runtime` (implementation).

JAVA-5647

Author: rozza

bson-scala/build.gradle

@@ -18,7 +18,7 @@ description = "A Scala wrapper / extension to the bson library"
 archivesBaseName = 'mongo-scala-bson'
 
 dependencies {
-    implementation project(path: ':bson', configuration: 'default')
+    api project(path: ':bson', configuration: 'default')
 }
 
 sourceSets {

build.gradle

@@ -109,15 +109,16 @@ configure(javaProjects) {
 
 configure(scalaProjects) {
     apply plugin: 'scala'
+    apply plugin: 'java-library'
     apply plugin: 'idea'
     apply plugin: "com.adtran.scala-multiversion-plugin"
     apply plugin: "com.diffplug.spotless"
 
     group = 'org.mongodb.scala'
 
     dependencies {
-        implementation ('org.scala-lang:scala-library:%scala-version%')
-        implementation ('org.scala-lang:scala-reflect:%scala-version%')
+        api ('org.scala-lang:scala-library:%scala-version%')
+        api ('org.scala-lang:scala-reflect:%scala-version%')
 
         testImplementation(platform("org.junit:junit-bom:$junitBomVersion"))
         testImplementation("org.junit.vintage:junit-vintage-engine")

driver-scala/build.gradle

@@ -19,8 +19,8 @@ archivesBaseName = 'mongo-scala-driver'
 
 
 dependencies {
-    implementation project(path: ':bson-scala', configuration: 'default')
-    implementation project(path: ':driver-reactive-streams', configuration: 'default')
+    api project(path: ':bson-scala', configuration: 'default')
+    api project(path: ':driver-reactive-streams', configuration: 'default')
     compileOnly 'com.google.code.findbugs:jsr305:1.3.9'
 
     testImplementation project(':driver-sync')