src/main/java/ognl/OgnlOps.java
public static BigInteger bigIntValue(Object value)
        throws NumberFormatException
    {
        if (value == null) return BigInteger.valueOf(0L);
        Class c = value.getClass();
        if (c == BigInteger.class) return (BigInteger) value;
        if (c == BigDecimal.class) return ((BigDecimal) value).toBigInteger();
        if (c.getSuperclass() == Number.class) return BigInteger.valueOf(((Number) value).longValue());
        if (c == Boolean.class) return BigInteger.valueOf(((Boolean) value).booleanValue() ? 1 : 0);
        if (c == Character.class) return BigInteger.valueOf(((Character) value).charValue());
        return new BigInteger(stringValue(value, true));
    }
public static BigInteger bigIntValue(Object value)
        throws NumberFormatException
    {
        if (value == null) return BigInteger.valueOf(0L);
        Class c = value.getClass();
        if (c == BigInteger.class) return (BigInteger) value;
        if (c == BigDecimal.class) return ((BigDecimal) value).toBigInteger();
        if (c.getSuperclass() == Number.class) return BigInteger.valueOf(((Number) value).longValue());
        if (c == Boolean.class) return BigInteger.valueOf(((Boolean) value).booleanValue() ? 1 : 0);
        if (c == Character.class) return BigInteger.valueOf(((Character) value).charValue());
        return new BigInteger(stringValue(value, true));
    }
Evaluates the given object as a BigInteger.

@param value
an object to interpret as a BigInteger
@return the BigInteger value implied by the given object
@throws NumberFormatException
if the given object can't be understood as a BigInteger