SI-7265 General test for spec version

The test for isJavaAtLeast uses the specification.version.

The method argument must have the form "major.minor".

The scaladoc is updated to reflect the new reality and a
test is added under junit.

For 2.10.x, javaSpecVersion is provided as a private member.
The active test is under `run` and the `junit` test must
bide its time in `pending`.