org.xml.sax.SAXParseException: Failed to read camel-spring-2.23.2.xsd

Issue

• Within the camel-context.xml file, I have set the camel-spring-2.23.2.xsd and included a setHeader element:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="        http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd        http://camel.apache.org/schema/spring        http://camel.apache.org/schema/spring/camel-spring-2.23.2.xsd">
    <camelContext id="camel" xmlns="http://camel.apache.org/schema/spring">
        <route id="simple-route">
            <from id="route-timer" uri="timer://foo?period=1000"/>
            <setHeader headerName="SOURCE_SYSTEM">
              <constant>VBS</constant>
            </setHeader>
            <setBody id="route-setBody">
                <simple>Hello World from camel-context.xml</simple>
            </setBody>
            <log id="route-log" message=">>> ${body}"/>
        </route>
    </camelContext>
</beans>

• The XSD file should be loaded from the Fuse JAR files. However, if we disconnect from the network, you can see that it fails to load the XSD:

org.xml.sax.SAXParseException: schema_reference.4: Failed to read schema document 'http://camel.apache.org/schema/spring/camel-spring-2.23.2.xsd', because 1) could not find the document; 2) the document could not be read; 3) the root element of the document is not <xsd:schema>.
. . . . .
Caused by: java.net.UnknownHostException: camel.apache.org