[build] Fixed trace file inclusion, updated Xtend plugin to 1.0.15

build.gradle

@@ -9,7 +9,7 @@ buildscript {
 	apply from: "${rootDir}/gradle/versions.gradle"
 	repositories.jcenter()
 	dependencies {
-		classpath "org.xtext:xtext-gradle-plugin:$versions.xtend_plugin"
+		classpath "org.xtext:xtext-gradle-plugin:$versions.xtext_gradle_plugin"
 		classpath "io.typefox.gradle:gradle-p2gen:$versions.gradle_plugins"
 	}
 }

gradle/bootstrap-setup.gradle

@@ -32,5 +32,5 @@ configurations {
 dependencies {
 	xtendCompiler "org.eclipse.xtend:org.eclipse.xtend.core:$bootstrapXtendVersion"
 	xtendCompiler "org.eclipse.xtext:org.eclipse.xtext.smap:$bootstrapXtendVersion"
-	xtendCompiler "org.xtext:xtext-gradle-builder:$versions.xtend_plugin"
+	xtendCompiler "org.xtext:xtext-gradle-builder:$versions.xtext_gradle_plugin"
 }

gradle/versions.gradle

@@ -8,7 +8,7 @@ ext.versions = [
 	'xtext': version,
 	'xtext_bootstrap': '2.11.0.beta2',
 	'gradle_plugins': '0.1.0',
-	'xtend_plugin': '1.0.14',
+	'xtext_gradle_plugin': '1.0.15',
 	'lsp4j': '0.1.0-SNAPSHOT',
 	'log4j': '1.2.16',
 	'equinoxCommon' : '3.8.0',

gradle/xtend-compiler-settings.gradle

@@ -7,14 +7,17 @@ if (findProperty('compileXtend') == 'true') {
 		gen.xtextClasspath = rootProject.configurations.getByName('xtendCompiler')
 	}
 	
-	sourcesJar {
-		from (sourceSets.main.xtendOutputDir) {
-			include '**/*._trace'
-		}
-		if (name.endsWith('tests')) {
-			from (sourceSets.test.xtendOutputDir) {
+	// Defer the sources jar configuration to later when the source sets are set up completely
+	afterEvaluate {
+		sourcesJar {
+			from (sourceSets.main.xtendOutputDir) {
 				include '**/*._trace'
 			}
+			if (name.endsWith('tests')) {
+				from (sourceSets.test.xtendOutputDir) {
+					include '**/*._trace'
+				}
+			}
 		}
 	}
 }