presto-main/src/main/java/io/prestosql/sql/analyzer/Analysis.java/Analysis/isColumnReference
class Analysis:    public boolean isColumnReference(Expression expression)
    {
        requireNonNull(expression, "expression is null");
        checkArgument(getType(expression) != null, "expression %s has not been analyzed", expression);
        return columnReferences.containsKey(NodeRef.of(expression));
    }