我无法在我的tomcat9.0.12服务器上运行我的java servelet，因为它无法处理类版本。我得到以下错误：

Error: MyClass been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0 (unable to load class

我用java 11编译了我的代码：

<plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.0</version>
                <configuration>
                    <source>11</source>
                    <target>11</target>
                </configuration>
            </plugin>

当我输入：java版本在我的终端我得到：

java version "11.0.2" 2019-01-15 LTS
Java(TM) SE Runtime Environment 18.9 (build 11.0.2+9-LTS)
Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.2+9-LTS, mixed mode)

对于javac -版本

javac 11.0.2

为什么运行时不能处理v55.0？java 11 == v55.0？！