The package com.google.appengine.api.urlfetch cannot be found - google-app-engine

Question

We are trying to use a URL fetcher to retrieve get the response of an GAE API method, using the following code. As far as I'm aware this code is correct, but there seems to be a problem with the imports. Am I missing a dependency from the gradle build file perhaps? Have looked around on the internet but haven't got anywhere.
import com.google.appengine.api.urlfetch.HTTPHeader;
import com.google.appengine.api.urlfetch.HTTPResponse;
import com.google.appengine.api.urlfetch.URLFetchService;
import com.google.appengine.api.urlfetch.URLFetchServiceFactory;
import java.io.IOException;
import java.net.URL;
import java.util.List;
…
URLFetchService fetcher = URLFetchServiceFactory.getURLFetchService();
try {
URL url = new URL("<URL we use is redacted>");
HTTPResponse response = fetcher.fetch(url);
byte[] content = response.getContent();
// if redirects are followed, this returns the final URL we are redirected to
URL finalUrl = response.getFinalUrl();
// 200, 404, 500, etc
int responseCode = response.getResponseCode();
List < HTTPHeader > headers = response.getHeaders();
for (HTTPHeader header: headers) {
String headerName = header.getName();
String headerValue = header.getValue();
System.out.println(headerName + " " + headerValue);
}
} catch (IOException e) {
// new URL throws MalformedUrlException, which is impossible for us here
}
We are getting the following error:
/Users/Michael/Documents/GradeMe/app/src/main/java/com/ip/grademe/Register.java
Error:(12, 41) error: package com.google.appengine.api.urlfetch does not exist
Error:(13, 41) error: package com.google.appengine.api.urlfetch does not exist
Error:(14, 41) error: package com.google.appengine.api.urlfetch does not exist
Error:(15, 41) error: package com.google.appengine.api.urlfetch does not exist
Error:(73, 17) error: cannot find symbol class URLFetchService
Error:(73, 43) error: cannot find symbol variable URLFetchServiceFactory
Error:(77, 21) error: cannot find symbol class HTTPResponse
Error:(85, 26) error: cannot find symbol class HTTPHeader
Error:(87, 25) error: cannot find symbol class HTTPHeader
EDIT: The gradle.build file
apply plugin: 'com.android.application'
android {
compileSdkVersion 21
buildToolsVersion "21.1.2"
defaultConfig {
applicationId "com.ip.grademe"
minSdkVersion 14
targetSdkVersion 21
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:22.0.0'
compile project(path: ':backend', configuration: 'android-endpoints')
}