Firebase send request with oauth2 token example not working - firebase

Question

Trying to get simple google oauth example from Firebase docs to work using Firebase service account json file https://firebase.google.com/docs/cloud-messaging/auth-server#windows :
private static String getAccessToken() throws IOException {
GoogleCredentials googleCredentials = GoogleCredentials
.fromStream(new FileInputStream("service-account.json"))
.createScoped(Arrays.asList(SCOPES));
googleCredentials.refreshAccessToken();
return googleCredentials.getAccessToken().getTokenValue();
} //Messaging.java
Following is my code in Netbeans IDE:
import com.google.auth.oauth2.GoogleCredentials;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Arrays;
import java.util.logging.Level;
import java.util.logging.Logger;
/*
* Click nbfs://nbhost/SystemFileSystem/Templates/Licenses/license-default.txt to change this license
* Click nbfs://nbhost/SystemFileSystem/Templates/Project/Maven2/JavaApp/src/main/java/${packagePath}/${mainClassName}.java to edit this template
*/
/**
*
* #author Administrator
*/
public class TrOauth2 {
private static final String MESSAGING_SCOPE = "https://www.googleapis.com/auth/firebase.messaging";
private static final String[] SCOPES = {MESSAGING_SCOPE};
private static String comeon;
public static void main(String[] args) {
try {
System.out.println("Hello World!");
comeon = getAccessToken();
System.out.println(comeon);
} catch (IOException ex) {
Logger.getLogger(TrOauth2.class.getName()).log(Level.SEVERE, null, ex);
System.out.println("Exception when calling getAcessToken();");
}
}
private static String getAccessToken() throws FileNotFoundException, IOException {
GoogleCredentials googleCredentials = GoogleCredentials.fromStream(new FileInputStream("C:\\Users\\administrator\\Downloads\\lora-alarm-firebase-adminsdk-xxx-xxx.json")).createScoped(Arrays.asList(SCOPES));
System.out.println("googleCredentials: " + googleCredentials.toString());
return googleCredentials.getAccessToken().getTokenValue();
}
}
Maven code:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.midniteit</groupId>
<artifactId>TrOauth2</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>12</maven.compiler.source>
<maven.compiler.target>12</maven.compiler.target>
<exec.mainClass>TrOauth2</exec.mainClass>
</properties>
<dependencies>
<dependency>
<groupId>com.google.oauth-client</groupId>
<artifactId>google-oauth-client</artifactId>
<version>1.34.1</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.13.4</version>
</dependency>
<dependency>
<groupId>com.google.protobuf</groupId>
<artifactId>protobuf-java</artifactId>
<version>3.6.1</version>
</dependency>
<dependency>
<groupId>xpp3</groupId>
<artifactId>xpp3</artifactId>
<version>1.1.4c</version>
</dependency>
<dependency>
<groupId>com.google.auth</groupId>
<artifactId>google-auth-library-oauth2-http</artifactId>
<version>1.11.0</version>
<type>jar</type>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>3.0.0</version>
<configuration>
<mainClass>TrOauth2</mainClass>
</configuration>
<executions>
<execution>
<id>execute-after-compile</id>
<goals><goal>java</goal></goals>
<phase>compile</phase>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
I get the following results from Netbeans IDE when I run it:
Hello World!
googleCredentials: ServiceAccountCredentials{clientId=xxx, clientEmail=firebase-adminsdk-xxx#lora-alarm.iam.gserviceaccount.com, privateKeyId=xxx, transportFactoryClassName=com.google.auth.oauth2.OAuth2Utils$DefaultHttpTransportFactory, tokenServerUri=https://oauth2.googleapis.com/token, scopes=[https://www.googleapis.com/auth/firebase.messaging], defaultScopes=[], serviceAccountUser=null, quotaProjectId=null, lifetime=3600, useJwtAccessWithScope=false, defaultRetriesEnabled=true}
java.lang.NullPointerException
at TrOauth2.getAccessToken (TrOauth2.java:43)
at TrOauth2.main (TrOauth2.java:29)
at org.codehaus.mojo.exec.ExecJavaMojo$1.run (ExecJavaMojo.java:254)
at java.lang.Thread.run (Thread.java:835)
------------------------------------------------------------------------
BUILD FAILURE
------------------------------------------------------------------------
When I run program through command line, I get this, without the googleCredentials line being printed:
C:\Users\administrator\Documents\NetBeansProjects\TrOauth2\target\classes>"c:\progra~1\java\jdk-12~1.1\bin\java" TrOauth2
Hello World!
Exception in thread "main" java.lang.NoClassDefFoundError: com/google/auth/oauth2/GoogleCredentials
at TrOauth2.getAccessToken(TrOauth2.java:41)
at TrOauth2.main(TrOauth2.java:29)
Caused by: java.lang.ClassNotFoundException: com.google.auth.oauth2.GoogleCredentials
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:583)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
... 2 more
How is this happening, or what might I be doing wrong? Any ideas would be appreciated.