类存放在与包指定的目录不同的目录中 - 为什么？

robert@neghvar:~/tmp> cat org/foo/Bar.java 
public class Bar {

}

robert@neghvar:~/tmp> javac org/foo/Bar.java 
robert@neghvar:~/tmp> javap org.foo.Bar
Compiled from "Bar.java"
public class org.something.Bar extends java.lang.Object{
    public org.something.Bar();
}

org/foo

org.something