ADDITIONAL SYSTEM INFORMATION :
JDK 22.0.1

A DESCRIPTION OF THE PROBLEM :
MutableBigInteger's methods addShifted(MutableBigInteger addend, int n) and addDisjoint(MutableBigInteger addend, int n) implicitly assume that (addend.offset + addend.intLen == addend.value.length)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
MutableBigInteger a = new MutableBigInteger();
MutableBigInteger b = new MutableBigInteger(new int[] { 1, 0, 0, 0, 0, 1, 0 });
a.addDisjoint(b, 4); // or a.addShifted(b, 4);

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
a.offset == 0 && a.intLen == 8 && Arrays.equals(a.value, new int[] { 1, 0, 0, 0, 0, 0, 0, 0 })
ACTUAL -
a.offset == 0 && a.intLen == 8 && Arrays.equals(a.value, new int[] { 1, 0, 0, 0, 0, 1, 0, 0 })

CUSTOMER SUBMITTED WORKAROUND :
In MutableBigInteger.java replace the instructions
for addShifted:
- in line 818 -> int bval = y < addend.intLen ? addend.value[y+addend.offset] : 0;
- in line 837 -> int bval = y < addend.intLen ? addend.value[y+addend.offset] : 0;

for addDisjoint:
- in line 889 -> int len = Math.min(y, addend.intLen);

FREQUENCY : occasionally