Apparently interface methods can sometimes appear directly in expression trees, i.e. not their interface, but the method itself.  If I check for that too, IEquatable.Equals is correctly detected in the test.
Apparently interface methods can sometimes appear directly in expression trees, i.e. not their interface, but the method itself.  If I check for that too, IEquatable.Equals is correctly detected in the test.

asd-and-Rizzo/ExpressionToCode,EamonNerbonne/ExpressionToCode