Move helloworld samples from getting-started-java (#3010)

Fixes #issue

> It's a good idea to open an issue first for discussion.

- [ ] I have followed [Sample Format Guide](https://github.com/GoogleCloudPlatform/java-docs-samples/blob/master/SAMPLE_FORMAT.md)
- [ ] `pom.xml` parent set to latest `shared-configuration`
- [ ] Appropriate changes to README are included in PR
- [ ] API's need to be enabled to test (tell us)
- [ ] Environment Variables need to be set (ask us to set them)
- [ ] Tests pass (`mvn -P lint clean verify`)
  * (Note- `Checkstyle` passing is required; `Spotbugs`, `ErrorProne`, `PMD`, etc. `ERROR`'s are advisory only)
- [ ] Please **merge** this PR for me once it is approved.

appengine-java8/helloworld/README.md

@@ -0,0 +1,91 @@
+HelloWorld for App Engine Standard (Java 8)
+============================
+
+This sample demonstrates how to deploy an application on Google App Engine.
+
+See the [Google App Engine standard environment documentation][ae-docs] for more
+detailed instructions.
+
+[ae-docs]: https://cloud.google.com/appengine/docs/java/
+
+
+* [Java 8](http://www.oracle.com/technetwork/java/javase/downloads/index.html)
+* [Maven](https://maven.apache.org/download.cgi) (at least 3.5)
+* [Gradle](https://gradle.org/gradle-download/) (optional)
+* [Google Cloud SDK](https://cloud.google.com/sdk/) (aka gcloud)
+
+## Setup
+
+• Download and initialize the [Cloud SDK](https://cloud.google.com/sdk/)
+
+```
+gcloud init
+```
+
+* Create an App Engine app within the current Google Cloud Project
+
+```
+gcloud app create
+```
+
+* In the `pom.xml`, update the [App Engine Maven Plugin](https://cloud.google.com/appengine/docs/standard/java/tools/maven-reference)
+with your Google Cloud Project Id:
+
+```
+<plugin>
+  <groupId>com.google.cloud.tools</groupId>
+  <artifactId>appengine-maven-plugin</artifactId>
+  <version>2.2.0</version>
+  <configuration>
+    <projectId>myProjectId</projectId>
+    <version>GCLOUD_CONFIG</version>
+  </configuration>
+</plugin>
+```
+**Note:** `GCLOUD_CONFIG` is a special version for autogenerating an App Engine
+version. Change this field to specify a specific version name.
+
+## Maven
+### Running locally
+
+    mvn package appengine:run
+
+To use vist: http://localhost:8080/
+
+### Deploying
+
+    mvn package appengine:deploy
+
+To use vist:  https://YOUR-PROJECT-ID.appspot.com
+
+## Gradle
+### Running locally
+
+    gradle appengineRun
+
+If you do not have gradle installed, you can run using `./gradlew appengineRun`.
+
+To use vist: http://localhost:8080/
+
+### Deploying
+
+    gradle appengineDeploy
+
+If you do not have gradle installed, you can deploy using `./gradlew appengineDeploy`.
+
+To use vist:  https://YOUR-PROJECT-ID.appspot.com
+
+## Testing
+
+    mvn verify
+
+ or
+
+    gradle test
+
+As you add / modify the source code (`src/main/java/...`) it's very useful to add [unit testing](https://cloud.google.com/appengine/docs/java/tools/localunittesting)
+to (`src/main/test/...`).  The following resources are quite useful:
+
+* [Junit4](http://junit.org/junit4/)
+* [Mockito](http://mockito.org/)
+* [Truth](http://google.github.io/truth/)

appengine-java8/helloworld/build.gradle

@@ -0,0 +1,86 @@
+// Copyright 2017 Google Inc.
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//        http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+// [START gradle]
+buildscript {    // Configuration for building
+  repositories {
+    jcenter()    // Bintray's repository - a fast Maven Central mirror & more
+    mavenCentral()
+  }
+  dependencies {
+    classpath 'com.google.cloud.tools:appengine-gradle-plugin:2.2.0' // If a newer version is available, use it
+  }
+}
+
+repositories {   // repositories for Jar's you access in your code
+  maven {
+    url 'https://oss.sonatype.org/content/repositories/snapshots' // SNAPSHOT repository (if needed)
+  }
+  mavenCentral()
+  jcenter()
+}
+
+apply plugin: 'java'                              // standard Java tasks
+apply plugin: 'war'                               // standard Web Archive plugin
+apply plugin: 'com.google.cloud.tools.appengine'  // App Engine tasks
+
+dependencies {
+  compile 'com.google.appengine:appengine-api-1.0-sdk:+'  // Latest App Engine Api's
+  providedCompile 'javax.servlet:javax.servlet-api:3.1.0'
+
+  compile 'jstl:jstl:1.2'
+
+// Add your dependencies here.
+//  compile 'com.google.cloud:google-cloud:+'   // Latest Cloud API's http://googlecloudplatform.github.io/google-cloud-java
+
+  testCompile 'junit:junit:4.12'
+  testCompile 'com.google.truth:truth:0.33'
+  testCompile 'org.mockito:mockito-all:1.10.19'
+
+  testCompile 'com.google.appengine:appengine-testing:+'
+  testCompile 'com.google.appengine:appengine-api-stubs:+'
+  testCompile 'com.google.appengine:appengine-tools-sdk:+'
+}
+
+// Always run unit tests
+appengineDeploy.dependsOn test
+appengineStage.dependsOn test
+
+appengine {  // App Engine tasks configuration
+  deploy {   // deploy configuration
+    projectId = System.getenv('GOOGLE_CLOUD_PROJECT')
+    version = '1'
+  }
+}
+
+test {
+  useJUnit()
+  testLogging.showStandardStreams = true
+  beforeTest { descriptor ->
+     logger.lifecycle("test: " + descriptor + "  Running")
+  }
+
+  onOutput { descriptor, event ->
+     logger.lifecycle("test: " + descriptor + ": " + event.message )
+  }
+  afterTest { descriptor, result ->
+    logger.lifecycle("test: " + descriptor + ": " + result )
+  }
+}
+
+group   = "com.example.appenginej8"        // Generated output GroupId
+version = "1.0-SNAPSHOT"       // Version in generated output
+
+sourceCompatibility = 1.8     // App Engine Flexible uses Java 8
+targetCompatibility = 1.8     // App Engine Flexible uses Java 8
+// [END gradle]

appengine-java8/helloworld/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,6 @@
+#Tue Jun 13 16:53:48 PDT 2017
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.4.1-bin.zip

appengine-java8/helloworld/gradlew

@@ -0,0 +1,172 @@
+#!/usr/bin/env sh
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn ( ) {
+    echo "$*"
+}
+
+die ( ) {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save ( ) {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=$(save "$@")
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+  cd "$(dirname "$0")"
+fi
+
+exec "$JAVACMD" "$@"