Invalid minimal value of datasource background-validation-millis parameter

Regarding .../docs/schema/ jboss-as-datasources_1_0.xsd

the background-validation-millis type is defined like "nonNegativeInteger"
<xs:element name="background-validation-millis" type="xs:nonNegativeInteger" minOccurs="0">

and nonNegativeInteger is: "An integer containing only non-negative values (0,1,2,..)"

thus zero is valid value to add...