Java XPath processors ignoring namespace context

I'm trying to query an XML document with a default namespace. I want to get the text content of a node in the default namespace.

I believe I've set things up correctly. However, I'm not getting results. I've created a NamespaceContext and passed it to the XPath processor. From the output it doesn't look like the context is being referenced. As such, the namespace-aware processor isn't finding the nodes in the default namespace.

When I try the query with a very ugly XPath expression that ignores namespaces, I get the expected result.

I've included an example program, the XML file being queried and the output.

Thanks.

The program

import java.io.IOException;
import java.io.StringReader;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Iterator;
import java.util.List;

import javax.xml.XMLConstants;
import javax.xml.namespace.NamespaceContext;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;

import org.xml.sax.InputSource;

public class Example {

    public static void main(String[] args) throws IOException, XPathExpressionException {
        List<String> pomLines = Files.readAllLines(Paths.get("example.xml"));
        String document = String.join(System.lineSeparator(), pomLines);

        // XPathFactory xpathFactory = new net.sf.saxon.xpath.XPathFactoryImpl();
        XPathFactory xpathFactory = XPathFactory.newInstance();
        XPath xpathNS = xpathFactory.newXPath();
        xpathNS.setNamespaceContext(new NamespaceContext() {

            @Override
            public String getNamespaceURI(String prefix) {
                System.out.println("*** getNamespaceURI, prefix='" + prefix + "'");
                if (prefix.equals(XMLConstants.DEFAULT_NS_PREFIX)) {
                    System.out.println("*** returning a URL");
                    return "http://maven.apache.org/POM/4.0.0";
                }

                System.out.println("*** returning NULL_NS_URI");
                return XMLConstants.NULL_NS_URI;
            }

            @Override
            public String getPrefix(String namespaceURI) {
                throw new UnsupportedOperationException("Not supported yet.");
            }

            @Override
            public Iterator<String> getPrefixes(String namespaceURI) {
                throw new UnsupportedOperationException("Not supported yet.");
            }
        });

        XPathExpression xpathExpressionNS = xpathNS.compile("/project/name/text()");
        String artifactIdNS = xpathExpressionNS
                .evaluate(new InputSource(new StringReader(document)));
        System.out.println("artifactIdNS='" + artifactIdNS + "'");
        XPath xpath = xpathFactory.newXPath();
        XPathExpression xpathExpression = xpath
                .compile("/*[local-name()='project']/*[local-name()='name']/text()");
        String artifactId = xpathExpression.evaluate(new InputSource(new StringReader(document)));
        System.out.println("artifactId='" + artifactId + "'");

    }
}

The XML document

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>com.example</groupId>
        <artifactId>parent-test-repo</artifactId>
        <version>0.1.0</version>
    </parent>

    <artifactId>test-repo-1</artifactId>
    <name>test-repo-1</name>
    <version>1.1.0</version>
</project>

Actual output

~/temp% java Example
artifactIdNS=''
artifactId='test-repo-1'

I would have expected some lines with ***.