java unit tests should test with older api versions.

currently, we do stuff like this:
```
FDB fdb = FDB.selectAPIVersion(630);
```
instead, we should use something like this made-up static method:
```
FDB fdb = FDBTest.selectRandomAPIVersionAbove(500);
```
and there should be a way to tell it to always run at version 500, version current, or (by default) in-between. We could use a parameterized testing harness to run all three variants automatically.

Start by locating the Java unit tests that hard-code calls such as FDB.selectAPIVersion(630) and identify the parameterized testing framework they use. Define how tests should select version 500, the current version, or an in-between version, and confirm that all three variants run automatically.

Written by the indexing model from the issue text.