Test the Gradle plugin against Gradle 4.6

Closes gh-12314

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/plugin/KotlinPluginActionIntegrationTests.java

@@ -48,7 +48,8 @@ public class KotlinPluginActionIntegrationTests {
 				.build("kotlinVersion", "dependencies", "--configuration", "compile")
 				.getOutput();
 		assertThat(output).contains("Kotlin version: 1.2.10");
-		assertThat(output).contains("org.jetbrains.kotlin:kotlin-stdlib-jdk8: -> 1.2.10");
+		assertThat(output)
+				.containsPattern("org.jetbrains.kotlin:kotlin-stdlib-jdk8:* -> 1.2.10");
 	}
 
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/plugin/JavaPluginActionIntegrationTests-additionalMetadataLocationsConfiguredWhenProcessorIsPresent.gradle

@@ -12,7 +12,8 @@ repositories {
 }
 
 dependencies {
-	compile name: 'spring-boot-configuration-processor-1.2.3'
+	def configurationName = GradleVersion.current().compareTo(GradleVersion.version("4.6")) >= 0 ? 'annotationProcessor': 'compile'
+	add(configurationName, [name: 'spring-boot-configuration-processor-1.2.3'])
 }
 
 compileJava {