Use HTTPS for external links from XML files where possible

See gh-16312

spring-boot-autoconfigure/src/test/resources/ehcache3.xml

@@ -3,8 +3,8 @@
 		xmlns='http://www.ehcache.org/v3'
 		xmlns:jsr107='http://www.ehcache.org/v3/jsr107'
 		xsi:schemaLocation="
-        http://www.ehcache.org/v3 http://www.ehcache.org/schema/ehcache-core-3.1.xsd
-        http://www.ehcache.org/v3/jsr107 http://www.ehcache.org/schema/ehcache-107-ext-3.1.xsd">
+        http://www.ehcache.org/v3 https://www.ehcache.org/schema/ehcache-core-3.1.xsd
+        http://www.ehcache.org/v3/jsr107 https://www.ehcache.org/schema/ehcache-107-ext-3.1.xsd">
 
 	<cache-template name="example">
 		<heap unit="entries">200</heap>

spring-boot-integration-tests/spring-boot-integration-tests-embedded-servlet-container/src/test/resources/pom-template.xml

 <?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">
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 	<modelVersion>4.0.0</modelVersion>
 	<parent>
 		<groupId>org.springframework.boot</groupId>

spring-boot-samples/spring-boot-sample-cache/src/main/resources/ehcache3.xml

 <config xmlns='http://www.ehcache.org/v3'
 		xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 		xmlns:jsr107="http://www.ehcache.org/v3/jsr107"
-		xsi:schemaLocation="http://www.ehcache.org/v3 http://www.ehcache.org/schema/ehcache-core-3.0.xsd
-							http://www.ehcache.org/v3/jsr107 http://www.ehcache.org/schema/ehcache-107-ext-3.0.xsd">
+		xsi:schemaLocation="http://www.ehcache.org/v3 https://www.ehcache.org/schema/ehcache-core-3.0.xsd
+							http://www.ehcache.org/v3/jsr107 https://www.ehcache.org/schema/ehcache-107-ext-3.0.xsd">
 	<cache alias="countries">
 		<expiry>
 			<ttl unit="seconds">600</ttl>

spring-boot-starters/src/main/assembly/starter-poms-assembly.xml

 <assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3"
 	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 http://maven.apache.org/xsd/assembly-1.1.3.xsd">
+	xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 https://maven.apache.org/xsd/assembly-1.1.3.xsd">
 	<id>starter-poms</id>
 	<formats>
 		<format>zip</format>

spring-boot-test/src/test/resources/org/springframework/boot/test/context/SpringBootTestXmlConventionConfigurationTests-context.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
 	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
-	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
-				http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
+	xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd
+				http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
 
 	<bean id="foo" class="java.lang.String">
 		<constructor-arg>

spring-boot/src/test/resources/org/springframework/boot/diagnostics/analyzer/nounique/consumer.xml

 <?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 http://www.springframework.org/schema/beans/spring-beans.xsd">
+	xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd">
 
 	<bean class="org.springframework.boot.diagnostics.analyzer.nounique.TestBeanConsumer"/>
 

spring-boot/src/test/resources/org/springframework/boot/diagnostics/analyzer/nounique/producer.xml

 <?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 http://www.springframework.org/schema/beans/spring-beans.xsd">
+	xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd">
 
 	<bean class="org.springframework.boot.diagnostics.analyzer.nounique.TestBean" name="xmlTestBean"/>