GCS SignedURL in java with metadata headers

pom.xml

<?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>
  <packaging>jar</packaging>
  <version>1.0-SNAPSHOT</version>

  <groupId>com.test.TestApp</groupId>
  <artifactId>TestApp</artifactId>

  <properties>
  </properties>

  <dependencies>

<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud</artifactId>
  <version>0.12.0-alpha</version>
</dependency>

<dependency><groupId>commons-codec</groupId><artifactId>commons-codec</artifactId><version>1.9</version></dependency>

  </dependencies>

  <build>
    <plugins>
     <plugin>
      <artifactId>maven-compiler-plugin</artifactId>
      <version>2.0.2</version>
      <configuration>
        <source>1.7</source>
        <target>1.7</target>
      </configuration>
     </plugin>

      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>exec-maven-plugin</artifactId>
        <version>1.2.1</version>
        <executions>
          <execution>
            <goals>
              <goal>java</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <mainClass>com.test.TestApp</mainClass>
        </configuration>
      </plugin>
    </plugins>
  </build>

</project>

TestApp.java

package com.test;

import com.google.cloud.storage.Bucket;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import java.util.Collection;
import java.util.Iterator;
import java.io.FileInputStream;

import com.google.auth.oauth2.GoogleCredentials;
import com.google.auth.oauth2.ServiceAccountCredentials;
import com.google.auth.oauth2.ComputeEngineCredentials;
//import com.google.auth.oauth2.AppEngineCredentials;

import com.google.cloud.storage.Blob;
import com.google.cloud.storage.Blob.BlobSourceOption;
import com.google.cloud.storage.BlobId;
import com.google.cloud.storage.BlobInfo;

import com.google.cloud.storage.Storage.SignUrlOption;
import java.util.concurrent.TimeUnit;
import java.net.URL;

import java.util.*;
import com.google.cloud.storage.*;


import java.net.URL;
import java.util.*;
import java.util.List;
import java.util.TimeZone;
import java.util.logging.Logger;

import java.net.URLEncoder;
import java.util.concurrent.TimeUnit;

import org.apache.commons.codec.binary.Base64;



public class TestApp {
	public static void main(String[] args) {
		TestApp tc = new TestApp();
	}

	public TestApp() {
		try
		{

ServiceAccountCredentials creds = ServiceAccountCredentials.fromStream(new FileInputStream("/home/srashid/gcp_misc/certs/GCPNETAppID-e65deccae47b.json"));

Storage storage_service = StorageOptions.newBuilder()
    .setCredentials(creds)
    .build()
    .getService();

URL signedUrl = storage_service.signUrl(
		BlobInfo.newBuilder("mineral-minutia-820", "a.txt")
		.build(),
		60,
		TimeUnit.SECONDS,
		Storage.SignUrlOption.httpMethod(HttpMethod.PUT));


 System.out.println(signedUrl);


// ------------------------------------------------------------------------------

System.out.println("<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>");

		String BUCKET_NAME = "mineral-minutia-820";
 		String OBJECT_NAME = "a.txt";
 		String SERVICE_ACCOUNT_EMAIL = "svc-2-429@mineral-minutia-820.iam.gserviceaccount.com";
 		String verb = "PUT";
 		long expiration = System.currentTimeMillis()/1000 + 60;
		String Canonicalized_Extension_Headers = "x-goog-meta-icecreamflavor:vanilla";


        byte[] sr = creds.sign(  (verb + "\n\n\n" + expiration + "\n" + Canonicalized_Extension_Headers + 
		"\n" + "/" + BUCKET_NAME + "/" + OBJECT_NAME  ).getBytes() );
        String url_signature = new String(Base64.encodeBase64( sr ));
        String signed_url = "https://storage.googleapis.com/" + BUCKET_NAME + "/" + OBJECT_NAME +
                    "?GoogleAccessId=" + SERVICE_ACCOUNT_EMAIL +
                    "&Expires=" + expiration +
                    "&Signature=" + URLEncoder.encode(url_signature, "UTF-8");

		System.out.println(signed_url);



		}
		catch (Exception ex) {
			System.out.println("Error:  " + ex);
		}

	}

}