Math.pow yields different result depending on java version

but was there a change in the java spec that causes the difference?

No.^* According to the Javadocs for Math.pow, a difference of up to one ULP (Unit in the Last Place) is permitted. If we take a look at your two values:

System.out.printf("%016x\n", Double.doubleToLongBits(1.1567055833133086));
System.out.printf("%016x\n", Double.doubleToLongBits(1.1567055833133089));

we get:

3ff281ddb6b6e675
3ff281ddb6b6e676

which indeed differ by one ULP.

What you’re seeing is probably due to slight differences in the sequence of floating-point instructions used by the JDK/JVM to implement these operations.

_{* At least, not so far as I know!}