//[START imports]
package com.example.helloendpoints;

import com.google.api.server.spi.config.Api;
import com.google.api.server.spi.config.ApiMethod;
import com.google.api.server.spi.response.NotFoundException;
import com.google.appengine.api.users.User;

import java.util.ArrayList;

import javax.inject.Named;
//[END imports]
 //[START api_def]

/**
 * Defines v1 of a helloworld API, which provides simple "greeting" methods.
 */
@Api(name = "helloworld",
    version = "v1",
    scopes = {Constants.EMAIL_SCOPE},
    clientIds = {Constants.WEB_CLIENT_ID, Constants.ANDROID_CLIENT_ID, Constants.IOS_CLIENT_ID},
    audiences = {Constants.ANDROID_AUDIENCE}
)
public class Greetings {

  public static ArrayList<HelloGreeting> greetings = new ArrayList<HelloGreeting>();

  static {
    greetings.add(new HelloGreeting("hello world!"));
    greetings.add(new HelloGreeting("goodbye world!"));
  }
//[END api_def]
//[START getgreetings]

  public HelloGreeting getGreeting(@Named("id") Integer id) throws NotFoundException {
    try {
      return greetings.get(id);
    } catch (IndexOutOfBoundsException e) {
      throw new NotFoundException("Greeting not found with an index: " + id);
    }
  }

  public ArrayList<HelloGreeting> listGreeting() {
    return greetings;
  }
//[END getgreetings]
//[START multiplygreetings]

  @ApiMethod(name = "greetings.multiply", httpMethod = "post")
  public HelloGreeting insertGreeting(@Named("times") Integer times, HelloGreeting greeting) {
    HelloGreeting response = new HelloGreeting();
    StringBuilder responseBuilder = new StringBuilder();
    for (int i = 0; i < times; i++) {
      responseBuilder.append(greeting.getMessage());
    }
    response.setMessage(responseBuilder.toString());
    return response;
  }
//[END multiplygreetings]
//[START auth] 

  @ApiMethod(name = "greetings.authed", path = "hellogreeting/authed")
  public HelloGreeting authedGreeting(User user) {
    HelloGreeting response = new HelloGreeting("hello " + user.getEmail());
    return response;
  }
//[END auth]
}

//[START import_statements]
package com.example.helloendpoints;

import com.google.api.server.spi.config.Api;
import com.google.api.server.spi.config.ApiMethod;
import com.google.api.server.spi.response.NotFoundException;
import com.google.appengine.api.users.User;

import java.util.ArrayList;

import javax.inject.Named;
//[END import_statements]
 //[START api_def]

/**
 * Defines v1 of a helloworld API, which provides simple "greeting" methods.
 */
@Api(name = "helloworld",
    version = "v1",
    scopes = {Constants.EMAIL_SCOPE},
    clientIds = {Constants.WEB_CLIENT_ID, Constants.ANDROID_CLIENT_ID, Constants.IOS_CLIENT_ID},
    audiences = {Constants.ANDROID_AUDIENCE}
)
public class Greetings {

  public static ArrayList<HelloGreeting> greetings = new ArrayList<HelloGreeting>();

  static {
    greetings.add(new HelloGreeting("hello world!"));
    greetings.add(new HelloGreeting("goodbye world!"));
  }
//[END api_def]
//[START getgreetings]

  public HelloGreeting getGreeting(@Named("id") Integer id) throws NotFoundException {
    try {
      return greetings.get(id);
    } catch (IndexOutOfBoundsException e) {
      throw new NotFoundException("Greeting not found with an index: " + id);
    }
  }

  public ArrayList<HelloGreeting> listGreeting() {
    return greetings;
  }
//[END getgreetings]
//[START multiplygreetings]

  @ApiMethod(name = "greetings.multiply", httpMethod = "post")
  public HelloGreeting insertGreeting(@Named("times") Integer times, HelloGreeting greeting) {
    HelloGreeting response = new HelloGreeting();
    StringBuilder responseBuilder = new StringBuilder();
    for (int i = 0; i < times; i++) {
      responseBuilder.append(greeting.getMessage());
    }
    response.setMessage(responseBuilder.toString());
    return response;
  }
//[END multiplygreetings]
//[START auth] 

  @ApiMethod(name = "greetings.authed", path = "hellogreeting/authed")
  public HelloGreeting authedGreeting(User user) {
    HelloGreeting response = new HelloGreeting("hello " + user.getEmail());
    return response;
  }
//[END auth]
}

Update Greetings.java