ALPN callback dropped: SPDY and HTTP/2 are disabled. Is alpn-boot on the boot class path?

Trying to get Apple push notifications to work with my Spring Boot project.

I'm using this apns-http2 for sending push notification. From their GitGub page:

Note: Ensure that you have Jetty's ALPN JAR (OkHttp requires it) in your boot classpath. See here for more information. This is required until Java 9 is released, as Java 8 does not have native support for HTTP/2.

So I added the vm option

Xbootclasspath/p:/Users/sarath/.m2/repository/org/mortbay/jetty/alpn/alpn-boot/8.1.9.v20160720//alpn-boot-8.1.9.v20160720.jar

in Intellij run configuration and everything works. I'm getting the push notification.

But when I deploy the war to tomcat and try to send the push notifications, I'm getting error:

20-Apr-2019 13:08:33.400 INFO [OkHttp https://api.development.push.apple.com/3/device/A704797F6E1E284FB081630184A26755B59593715E1CD543483C2136CE24D4FD] okhttp3.internal.Platform$JdkWithJettyBootPlatform.getSelectedProtocol ALPN callback dropped: SPDY and HTTP/2 are disabled. Is alpn-boot on the boot class path?
20-Apr-2019 13:08:34.935 INFO [OkHttp https://api.development.push.apple.com/3/device/A704797F6E1E284FB081630184A26755B59593715E1CD543483C2136CE24D4FD] okhttp3.internal.Platform$JdkWithJettyBootPlatform.getSelectedProtocol ALPN callback dropped: SPDY and HTTP/2 are disabled. Is alpn-boot on the boot class path?
20-Apr-2019 13:08:36.588 INFO [OkHttp https://api.development.push.apple.com/3/device/A704797F6E1E284FB081630184A26755B59593715E1CD543483C2136CE24D4FD] okhttp3.internal.Platform$JdkWithJettyBootPlatform.getSelectedProtocol ALPN callback dropped: SPDY and HTTP/2 are disabled. Is alpn-boot on the boot class path?
20-Apr-2019 13:08:38.109 INFO [OkHttp https://api.development.push.apple.com/3/device/A704797F6E1E284FB081630184A26755B59593715E1CD543483C2136CE24D4FD] okhttp3.internal.Platform$JdkWithJettyBootPlatform.getSelectedProtocol ALPN callback dropped: SPDY and HTTP/2 are disabled. Is alpn-boot on the boot class path?
failure: NotificationResponse{error=null, httpStatusCode=-1, responseBody='null', cause=java.io.IOException: unexpected end of stream on okhttp3.Address@d60ab6f0}

I'm not sure how to set alpn-boot on the boot class path. I tried executing

java -Xbootclasspath/p:/Users/sarath/.m2/repository/org/mortbay/jetty/alpn/alpn-boot/8.1.9.v20160720/alpn-boot-8.1.9.v20160720.jar

from command prompt. But this only shows some Java help commands. I don't know whether the jar is actually added to the boot class path.

I also tried using maven-surefire-plugin like it says here. But still getting the same error.

Here's my 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>

    <parent>
        <groupId>com.cinch</groupId>
        <artifactId>gch</artifactId>
        <version>2.0.0</version>
        <relativePath>../pom.xml</relativePath>
    </parent>

    <groupId>com.cinch.gch</groupId>
    <artifactId>apn</artifactId>
    <version>1.0.0</version>
    <packaging>war</packaging>
    <name>apn</name>
    <description>Contains push notification services</description>

    <properties>
        <java.version>1.8</java.version>
        <alpn-boot-version>8.1.9.v20160720</alpn-boot-version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-activemq</artifactId>
        </dependency>

        <dependency>
            <groupId>com.cinch.gch</groupId>
            <artifactId>core</artifactId>
            <version>1.0.0</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <dependency>
            <groupId>com.cinch</groupId>
            <artifactId>gch-cache</artifactId>
        </dependency>

        <dependency>
            <groupId>org.mortbay.jetty.alpn</groupId>
            <artifactId>alpn-boot</artifactId>
            <version>${alpn-boot-version}</version>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>com.clevertap.apns</groupId>
            <artifactId>apns-http2</artifactId>
            <version>1.0.3</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>

            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.6</version>
                <configuration>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>

            <plugin>
                <artifactId>maven-surefire-plugin</artifactId>
                <configuration>
                    <argLine>
                        -Xbootclasspath/p:/Users/sarath/.m2/repository/org/mortbay/jetty/alpn/alpn-boot/${alpn-boot-version}/alpn-boot-${alpn-boot-version}.jar
                    </argLine>
                </configuration>
            </plugin>

        </plugins>
        <finalName>gch-apn</finalName>
    </build>

</project>

I tried many other things and nothing seems to work.

As pointed out by AlexanderPavlov in the comments.

If it must be on bootpath then you have to put it somewhere and add -Xbootclasspath option to java command-line arguments in catalina.bat/.sh

I created a file called setenv.sh inside Tomcat_Home/bin/

setenv.sh

export CATALINA_OPTS="-Xbootclasspath/p:/Users/sarath/.m2/repository/org/mortbay/jetty/alpn/alpn-boot/8.1.9.v20160720//alpn-boot-8.1.9.v20160720.jar"

catalina.bat/.sh will automatically read setenv.sh if it is present.