Windchill PDMLink 12.0，Java 构建失败，出现错误消息：“src/ext/xxx/xxx.java:11: 错误：无法访问 WTChangeOrder2；类文件的版本错误为 55.0，应为 52.0”

Java build failed, below, not just change order but also change request

    [javac] src/ext/xxx/xxx.java:11: error: cannot access WTChangeOrder2
    [javac] import wt.change2.WTChangeOrder2;
    [javac]                  ^
    [javac]   bad class file: /u01/wc12/Windchill/codebase/wt/change2/WTChangeOrder2.class
    [javac]     class file has wrong version 55.0, should be 52.0
    [javac]     Please remove or make sure it appears in the correct subdirectory of the classpath.

BUILD FAILED