Includes operation returns false instead of null if either operand is null #1718
Description
To duplicate:
<?xml version="1.0" encoding="utf-8"?>
<tests xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://hl7.org/fhirpath/tests" xsi:schemaLocation="http://hl7.org/fhirpath/tests ../../testSchema/testSchema.xsd"
name="CqlListOperatorsTest">
<group name="SingleTest" version="1.0">
<test name="IncludesNullLeft" version="1.0">
<capability code="list-operators" />
<expression>null includes {2}</expression>
<output>null</output>
</test>
</group>
</tests>
actual: false
According to https://cql.hl7.org/09-b-cqlreference.html#includes "For the interval-interval overload, if either argument is null, the result is null."