Custom class for supporting primitive XSD data type nonPositiveInteger
nonPositiveInteger is derived from integer by setting the value of maxInclusive to be 0. This
results in the standard mathematical concept of the non-positive integers. The value space of
nonPositiveInteger is the infinite set {...,-2,-1,0}.
See Also:XML Schema 3.3.14
Inner Class :protected static class BigIntegerRep implements java.io.Serializable