Diamond operator is not supported

При попытке задеплоить телеграмм бота на heroku выдает ошибку

Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project TestBot: Compilation failure remote:
[ERROR] /tmp/build_31e640807cc4c7dde699ecf0c146d90e/src/main/java/com/bot/Main.java:[68,52] diamond operator is not supported in -source 1.5 remote:
[ERROR] (use -source 7 or higher to enable diamond operator)

Строка 68:

List keyboard = new ArrayList<>();

pom.xml

<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>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
      </properties>
    <groupId>org.example</groupId>
    <artifactId>TestBot</artifactId>
    <version>1.0-SNAPSHOT</version>
    <build>
        <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.6.1</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>appassembler-maven-plugin</artifactId>
                <version>1.1.1</version>
                <configuration>
                    <assembleDirectory>target</assembleDirectory>
                    <source>1.8</source>
                    <target>1.8</target>
                    <programs>
                        <program>
                            <mainClass>com.bot.Main</mainClass>
                            <name>workerBot</name>
                        </program>
                    </programs>
                </configuration>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>assemble</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
    <!-- https://mvnrepository.com/artifact/org.telegram/telegrambots -->
    <dependencies>
        <dependency>
            <groupId>org.telegram</groupId>
            <artifactId>telegrambots</artifactId>
            <version>4.9</version>
        </dependency>
    </dependencies>

    
</project>