protected final ModuleManager getManager() {
        return manager;
    }
The <code>ModuleProvider</code> is an implementation of a {@link ModuleDefine}.
<p>
And each moduleDefine can have one or more implementation, which depends on `application.yml`
oap-server/server-library/library-module/src/main/java/org/apache/skywalking/oap/server/library/module/ModuleProvider.java