Add toolJar compile error message

annotation/compiler/build.gradle

@@ -6,7 +6,7 @@ apply plugin: 'java'
 configurations {
     // adapted from https://android.googlesource.com/platform/frameworks/testing/+/976c423/espresso/espresso-lib/build.gradle
     // compileOnly dependencies will be repackaged, see rules in jarjar ant task below
-    jarjar 
+    jarjar
 }
 
 dependencies {
@@ -18,7 +18,11 @@ dependencies {
     compileOnly "com.google.code.findbugs:jsr305:${JSR_305_VERSION}"
     compile project(':annotation')
     // This is to support com.sun.tools.javac.util.List, currently used in RootModuleGenerator.
-    compile files(Jvm.current().getToolsJar())
+    def toolsJar = Jvm.current().getToolsJar()
+    if (!toolsJar)
+        throw new GradleException("tools.jar not found at your JAVA_HOME dir ${Jvm.current().getJavaHome().getAbsolutePath()}.\n Please resetting your jdk")
+    testCompile files(toolsJar)
+
     annotationProcessor "com.google.auto.service:auto-service:${AUTO_SERVICE_VERSION}"
 }
 
@@ -51,8 +55,8 @@ task jarjar(dependsOn: [tasks.compiledJar, configurations.compileOnly]) {
             jarjar(jarfile: repackagedJar) {
                 configurations.compileOnly.resolve().each {
                     zipfileset(src: it.absolutePath, excludes: [
-                        'META-INF/maven/**',
-                        'META-INF/services/javax.annotation.processing.Processor'
+                            'META-INF/maven/**',
+                            'META-INF/services/javax.annotation.processing.Processor'
                     ].join(','))
                 }
                 zipfileset(src: tasks.compiledJar.archivePath)