com.sun.xml.internal.messaging.saaj.util.Base64 broken for certain inputs

[LanceAndersen]

Previously tracked via: https://bugs.openjdk.java.net/browse/JDK-6962582

FULL PRODUCT VERSION :
java version "1.6.0_20"
Java(TM) SE Runtime Environment (build 1.6.0_20-b02-279-10M3065)
Java HotSpot(TM) 64-Bit Server VM (build 16.3-b01-279, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Windows XP Professional SP3
Darwin waldonbm-2.local 10.3.0 Darwin Kernel Version 10.3.0: Fri Feb 26 11:58:09 PST 2010; root:xnu-1504.3.12~1/RELEASE_I386 i386

A DESCRIPTION OF THE PROBLEM :
Firstly, please move this bug report to the right location. I could not find the right sport for this issue.

For certain inputs, in specific - three consecutive ? characters (question mark) the Base64.encode() method fails.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile the program attached and execute it.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
An encoded string
ACTUAL -
waldo@waldonbm Java $ java base64

???<
[B@735cda3f<
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 63
at com.sun.xml.internal.messaging.saaj.util.Base64.encode(Base64.java:146)
at base64.main(base64.java:8)

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 63
at com.sun.xml.internal.messaging.saaj.util.Base64.encode(Base64.java:146)
at base64.main(base64.java:8)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import com.sun.xml.internal.messaging.saaj.util.Base64;

public class base64 {
public static void main(String[] args) {
String x = "???";
System.out.println(">"+x+"<");
System.out.println(">"+x.getBytes()+"<");
System.out.println(">"+Base64.encode(x.getBytes())+"<");
}
}

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

CUSTOMER SUBMITTED WORKAROUND :
Use a 3rd party base64 encoder that does not fail under the input "???" or "????" or ...