Change from java plugin to java-library plugin

The java-library plugin is an extension of the older java plugin.
It introduces the api dependency configuration and helps us to get
the right scope in the generated POM.

build.gradle

@@ -23,7 +23,7 @@ ext {
 allprojects {
 	group = "org.springframework.webflow"
 
-	apply plugin: "java"
+	apply plugin: "java-library"
 	apply plugin: "io.spring.dependency-management"
 	apply plugin: "org.springframework.build.optional-dependencies"
 	apply from: "${rootProject.projectDir}/ide.gradle"

publish-maven.gradle

@@ -10,7 +10,7 @@ publishing {
       }
       versionMapping {
         usage('java-api') {
-          fromResolutionOf('runtimeClasspath')
+          fromResolutionOf('compileClasspath')
         }
         usage('java-runtime') {
           fromResolutionResult()

spring-webflow/spring-webflow.gradle

@@ -1,7 +1,7 @@
 description = "Spring Web Flow"
 
 dependencies {
-	implementation(project(":spring-binding"))
+	api(project(":spring-binding"))
 	implementation("org.springframework:spring-web")
 	implementation("org.springframework:spring-webmvc")