static boolean areBothProjections(AttributeValue a, AttributeValue b) {
        return a instanceof AttributeValueImpl.Projection && b instanceof AttributeValueImpl.Projection;
    }
Compares the given attribute values by flattening each side of the
comparison, and comparing each value.

<p>This method is necessary in order to support matching on projections
using projection semantics.

@param singleComparison Comparison to apply to each element.
@return Returns the created comparator.
smithy-model/src/main/java/software/amazon/smithy/model/selector/AttributeComparator.java