@Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        } else if (!(o instanceof NotExpression)) {
            return false;
        }
        NotExpression notNode = (NotExpression) o;
        return expression.equals(notNode.expression);
    }
Gets the contained expression to negate.

@return Returns the contained expression.
smithy-jmespath/src/main/java/software/amazon/smithy/jmespath/ast/NotExpression.java