Acquiring original SQL identifier from RexInputRef

[Jeremy Dyer]

Hello,

Is it possible to get the original SQL identifier from an instance of
RexInputRef? For example given a simple query like

SELECT id FROM employees WHERE fname = 'adam'

Instead of the ordinal name generated by RexInputRef ($11, for example). I
would like to find the original SQL identifier (fname, for example)

Thanks,
Jeremy Dyer