Having decided which method to call, Saxon has to convert the supplied XPath argument values to the Java objects required by this method.
If the expected type is Object, the supplied value must either be a singleton, or an empty sequence.
If it is an empty sequence, null will be passed. If it is a singleton node, an instance of net.sf.saxon.om.NodeInfo
will be passed. If it is a wrapped Java object, that Java object will be passed.
If it is a singleton atomic value, the value will be converted to the nearest equivalent Java object: for example
an xs:boolean becomes java.lang.Boolean, an xs:string becomes java.lang.String,
and so on. An untyped atomic value is treated as a string. An xs:integer (even if it belongs to a subtype such as
xs:short) is converted to a Java BigInteger. The more specialized XML Schema primitive types such as
xs:hexBinary and xs:duration are passed in their native Saxon representation (a subclass of
net.sf.saxon.value.AtomicValue).
If the expected type is one of the Saxon-specific classes (SequenceIterator,
ValueRepresentation,
Item,
Value,
AtomicValue,
SequenceExtent), then the value is passed unchanged. An error occurs if the supplied value contains
more than one item and the expected type does not allow this.
If the expected type implements java.util.Collection, Saxon attempts to convert each value in the supplied sequence
to the most appropriate Java class, following the same rules as when converting a singleton to java.lang.Object.
This process takes no account of parameterized collection types (such as List<String>). If the required
collection type accepts an java.util.ArrayList, Saxon will create an ArrayList to hold the values; otherwise
it will attempt to instantiate the required type of collection, which will only work if it is a concrete class with a zero-argument
public constructor (so it will fail, for example, if the required type is java.util.Set). If an empty sequence is
supplied as the argument value, this is converted to an empty Collection.
If the required type is an array, Saxon will attempt to create an array of the required type. This will not always succeed,
for example if the array has type X[] where X is an interface rather than a concrete class. If it is an array of items
or nodes, the nodes in the supplied sequence will be inserted into the array directly; if it is an array of a type such as
integer or
double, the sequence will first be atomized.
