Handle AssertJ deprecations in 3.22.0 through 3.24.0

[timtebeek]

3.24.0 (2023-01-06) Deprecated ObjectAssert(AtomicReference) (2795)

Instead, use assertThat(actual.get()) or AtomicReferenceAssert#hasValueSatisfying(Consumer).

3.23.0 (2022-05-31) Deprecated getCause and getRootCause for Throwable assertions.

Add more assertThat…​Exception alternatives

3.22.0 (2022-01-03) Deprecated encodedAsBase64 / decodedAsBase64 in favor of asBase64Encoded / asBase64Decoded

The next release after that with deprecations is 3.20.0 from 2021-06-15; not sure if those have been picked up, but one would assume so given the timeline.