Fix Gradle to use flattened POM file

Update the Gradle plugin to use version information from the
flattened POM.xml files.

See gh-9316

Author: philwebb

Diff for: spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/build.gradle

@@ -8,35 +8,13 @@ repositories {
 	mavenCentral()
 }
 
-def addDependency(configurationName, dependency) {
-	def coordinates = [
-		'group': dependency.groupId.text(),
-		'name': dependency.artifactId.text(),
-		'version': dependency.version.text()
-	]
-	dependencies {
-		add configurationName, coordinates
-	}
-}
-
-def effectivePomFile = file('target/effective-pom.xml')
-if (effectivePomFile.file) {
-	def pom = new XmlSlurper().parseText(file('target/effective-pom.xml').text)
-	pom.dependencies.dependency.each { dependency ->
-		def scope = dependency.scope.text()
-		if (scope == 'compile') {
-			addDependency scope, dependency
-		}
-		else if (scope == 'test') {
-			addDependency 'testCompile', dependency
-		}
-	}
-}
-
 dependencies {
 	compile localGroovy()
 	compile gradleApi()
+	compile fileTree(dir: 'target/dependencies/compile', include: '*.jar')
 	testCompile gradleTestKit()
+	testCompile 'org.apache.commons:commons-compress:1.13'
+	testCompile fileTree(dir: 'target/dependencies/test', include: '*.jar')
 }
 
 jar {

Diff for: spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/testkit/GradleBuild.java

@@ -196,7 +196,7 @@ private static String evaluateExpression(String expression) {
 			XPathFactory xPathFactory = XPathFactory.newInstance();
 			XPath xpath = xPathFactory.newXPath();
 			XPathExpression expr = xpath.compile(expression);
-			String version = expr.evaluate(new InputSource(new FileReader("pom.xml")));
+			String version = expr.evaluate(new InputSource(new FileReader(".flattened-pom.xml")));
 			return version;
 		}
 		catch (Exception ex) {