FULL PRODUCT VERSION :
java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux eos 3.11.0-24-generic #42-Ubuntu SMP Fri Jul 4 21:19:31 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

A DESCRIPTION OF THE PROBLEM :
java.net.URI.relativize fails to relativize two URIs if they only differ in casing within escapes. For example:

http://www.example.com/%4a/b/a cannot be relativized against http://www.example.com/%4A/b/.

Although RFC 2396 states in section 6 that "In general, the rules for equivalence and definition of a normal form, if any, are scheme dependent.", this is not consistent with URI's equals method.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile & run this:

import java.net.URI;

public class Test {
    public static void main(String[] args){
        URI u = URI.create("http://www.example.com/%4A/b/");
        URI v = URI.create("http://www.example.com/%4a/b/a");
        System.out.println(u.relativize(v));
    }
}


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Prints:

a
ACTUAL -
Prints:

http://www.example.com/%4a/b/a

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.net.URI;

public class Test {
    public static void main(String[] args){
        URI u = URI.create("http://www.example.com/%4A/b/");
        URI v = URI.create("http://www.example.com/%4a/b/a");
        assert(u.relativize(v).toString().equals("a"));
    }
}
    

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Normalize escapes by hand.