How to specify BeamSQL UDF for Numeric Types

I'm trying to add a User Defined Function (UDF) to a SqlTransform in a Beam pipeline, and the SQL parser doesn't seem to understand the function's type. The error i get is:

No match found for function signature IF(<BOOLEAN>, <NUMERIC>, <NUMERIC>)

I've tried defining this for a bunch of different types (Double, Float, Long, Integer), but don't see how i can write this generically in a way that Beam will understand.

Is there some way to give type hints to the UDF, to to write one that handles arbitrary numeric types?

Seems, you should use BigDecimal.

Here is a similar question: What is the equivalent Data type for Numeric in apache.beam.sdk.schemas.Schema.FieldType