NPE validating transformation

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = super.hashCode();

        if(this.value != null && !isMultiValued()) {
            if (this.value instanceof BigDecimal) {
                BigDecimal bd = (BigDecimal)this.value;
                int xsign = bd.signum();
                if (xsign == 0)
                    return 0;
                bd = bd.stripTrailingZeros();
                result =  prime * result + bd.hashCode();
            }

            result = prime * result + this.value.hashCode();
        }

        return this.value.hashCode();
    }