Coder is not verified as deterministic in ApproximateUnique.java

Calling input.getCoder() does not verify that the coder is deterministic. A possible example where this could present a problem is if the user's data is float, as the float coder is not deterministic [1].

[1] https://github.com/apache/beam/blob/4d7df122ca053828bd2c7dffa9f390ba2bd8678e/sdks/java/core/src/main/java/org/apache/beam/sdk/coders/FloatCoder.java#L70

Imported from Jira [BEAM-10922](https://issues.apache.org/jira/browse/BEAM-10922). Original Jira may contain additional context.
Reported by: monicadsong.

Start in ApproximateUnique.java by tracing the input.getCoder() call, then read the linked FloatCoder.java reference to understand the determinism concern. Locate the relevant Java test coverage and verify that nondeterministic coders are handled as intended; done means the behavior is covered by a passing test.

Written by the indexing model from the issue text.