Even with ErrorHandler, why is schema validation ending after the first error?

I’m working on schema validation. The goal is to take an XSD file and validate an incoming document against it. If there are errors, I want to capture all of them.

I’m getting only the first error in the ErrorHandler and then the processing ends. There’s lots of internet examples of people asking this same question, and the answer seems to be always what I’m doing (create a custom error handler).

Further, the documentation for the ErrorHandler interface has this to say about how the error method is supposed to work:

/**
 * <p>The SAX parser must continue to provide normal parsing
 * events after invoking this method: it should still be possible
 * for the application to process the document through to the end.
 * If the application cannot do so, then the parser should report
 * a fatal error even if the XML recommendation does not require
 * it to do so.</p>
 */

Note that this is a Java 13 example, but there's no reason it really needs to be (other than for concise xml text definition).

private String drugValidationSchema = """
                    <?xml version="1.0" encoding="UTF-8"?>
                    <schema xmlns="http://www.w3.org/2001/XMLSchema"
                    targetNamespace="https://www.company.com/Drug"
                    xmlns:apins="https://www.company.com/Drug" elementFormDefault="qualified">

                        <element name="drugRequest" type="apins:drugRequest"></element>

                        <element name="drugResponse" type="apins:drugResponse"></element>

                        <complexType name="drugRequest">
                            <sequence>
                                <element name="id" type="int"></element>
                            </sequence>
                        </complexType>

                        <complexType name="drugResponse">
                            <sequence>
                                <element name="id" type="int"></element>
                                <element name="drugClass" type="string"></element>
                                <element name="drugName" type="string"></element>
                            </sequence>
                        </complexType>
                    </schema>
                    """;

// This document has 3 errors in it based on the schema above:
// 1) idx instead of id
// 2) dugClass instead of drugClass
// 3) dugName instead of drugName
private String badDrugResponseXml = """
                    <?xml version="1.0" encoding="UTF-8"?>
                    <apins:drugResponse xmlns:apins="https://www.company.com/Drug" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="https://www.company.com/Drug Drug.xsd ">
                      <apins:idx>1</apins:idx>
                      <apins:dugClass>opioid</apins:dugClass>
                      <apins:dugName>Buprenorphine</apins:dugName>
                    </apins:drugResponse>
                    """;

/**
 * This test does nothing but send the desired files into the validation
 * process.  The goal is for the validation process to output 3 errors.
 * For reasons I don't understand, it will only output the first one and
 * stop the processing.
 */
@Test
void testWithValidator() {
    System.out.println("Test an entry with multiple errors: " + validateXMLSchema(drugValidationSchema, badDrugResponseXml));
    Assertions.assertTrue(true);
}


/**
 * This validator process seems to always stop after the first error is encountered.
 *
 * @param xsdPath   the actual XSD content as String
 * @param xmlPath   the actual xml document text as String.
 * @return          True if there are no errors, false otherwise. (planning to return details)
 */
static boolean validateXMLSchema(String xsdPath, String xmlPath){

    try {
        SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);

        Schema schema = factory.newSchema(new StreamSource(new StringReader(xsdPath)));

        Validator validator = schema.newValidator();

        List<Exception> exceptions = new ArrayList<>();
        // Add a custom handler to the validator.  The goal is to continue processing
        // the document so that ALL errors are captured.
        validator.setErrorHandler(new ErrorHandler() {
            @Override
            public void warning(SAXParseException exception) {
                exceptions.add(exception);
            }

            @Override
            public void fatalError(SAXParseException exception) {
                exceptions.add(exception);
            }

            @Override
            public void error(SAXParseException exception) {
                exceptions.add(exception);
            }
        });

        validator.validate(new StreamSource(new StringReader(xmlPath)));

        if (exceptions.size() > 0) {
            for (Exception ex : exceptions) {
                System.out.println("Error found: " + ex.getMessage());
            }
        }else {
            System.out.println("No errors.");
        }
    } catch (SAXException | IOException e) {
        System.out.println("Exception: "+e.getMessage());
        return false;
    }
    return true;
}

As the comments suggest, it is clear in debugging that the first error is reported via the results of the custom error handler, but processing does not continue and find the subsequent two errors.