java.io.File.getCanonicalPath() returns different values for same path

ADDITIONAL SYSTEM INFORMATION :
Ubuntu 18.04
JDK 8
JDK 11

A DESCRIPTION OF THE PROBLEM :
When using getCanonicalPath() function I've noticed that if I put a directory name in the middle of the path I want to canonicalize, it's possible to get a canonical path starting with /../

This may lead to confussion to users when using getCanonicalPath function if they use it to validate paths, since users would never assume a canonical path can start with /../

Imagine I want to avoid someone could read anything under /etc folder in my system within a java application, and I create a filter which reads a path entered by the user, let's say ../../../../../etc/hosts and canonicalize it to check if starts with "/etc". If the user input is /../../../../../a/../../etc/hosts, getCanonicalPath funtion will return /../etc/hosts, which won't match my filter and would allow the user to read my /etc/hosts file.

I really think it's assumed by everybody that a Canonical Path will never contain ".." so I don't understand this weird behaviour in the getCanonicalPath function

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
String path = "/../../../../../a/../../etc/hosts";
String canPath = new File(path).getCanonicalPath();
System.out.println(canPath);

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
/etc/hosts
ACTUAL -
/../etc/hosts

---------- BEGIN SOURCE ----------
import java.io.File;
import java.io.IOException;

public class CanonicalTest {
    public static void main(String args[])
    {
        try {
            String path = "/../../../../../a/../../etc/hosts";
            String canPath = new File(path).getCanonicalPath();
            System.out.println(canPath);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
---------- END SOURCE ----------

FREQUENCY : always