I have a method with the following signature: foo (Sample sample, Aliquot aliquot)

"foo" needs to alter a Sample object, either the first argument or from the second argument it can extract its Sample. For example:

foo (Sample sample, Aliquot aliquot) {
    Sample out = null;
    if (sample != null)
       out = sample
    else
       out = aliquot.getSample()

    return out;
}

But that is so un-elegant, other than reading the API a developer does not know the reference of the first argument overrides the Sample of the second argument.

Now, I could change "foo" to foo (SomeMagicalObject bar) where SomeMagicalObject is a tuple for Sample and Aliquot and holds some logic ... etc.

But I am wondering, are there some patterns for this question?