¿Why is the context of parameterNames and strings null in this code?

protected NameValue[] parseBody(SOAPBodyElement body, SOAPFactory f)
throws SOAPException {
Node parameterNames = body.getFirstChild();
NodeList strings = parameterNames.getChildNodes();
int length = strings.getLength();
System.out.println(parameterNames);
System.out.println(strings);
System.out.println(length);
.
.
.
}

The results of the outputs are:

[ParameterNames: null]
[ParameterNames: null]
1