Leverage spring.ignore.xml flag to avoid XmlBeanDefinitionReader

Closes gh-25338

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassBeanDefinitionReader.java

@@ -44,6 +44,7 @@ import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
 import org.springframework.context.annotation.ConfigurationCondition.ConfigurationPhase;
+import org.springframework.core.SpringProperties;
 import org.springframework.core.annotation.AnnotationAttributes;
 import org.springframework.core.env.Environment;
 import org.springframework.core.io.Resource;
@@ -68,6 +69,7 @@ import org.springframework.util.StringUtils;
  * @author Juergen Hoeller
  * @author Phillip Webb
  * @author Sam Brannen
+ * @author Sebastien Deleuze
  * @since 3.0
  * @see ConfigurationClassParser
  */
@@ -77,6 +79,14 @@ class ConfigurationClassBeanDefinitionReader {
 
 	private static final ScopeMetadataResolver scopeMetadataResolver = new AnnotationScopeMetadataResolver();
 
+	/**
+	 * Boolean flag controlled by a {@code spring.xml.ignore} system property that instructs Spring to
+	 * ignore XML, i.e. to not initialize the XML-related infrastructure.
+	 * <p>The default is "false".
+	 */
+	private static final boolean shouldIgnoreXml = SpringProperties.getFlag("spring.xml.ignore");
+	
+
 	private final BeanDefinitionRegistry registry;
 
 	private final SourceExtractor sourceExtractor;
@@ -349,6 +359,9 @@ class ConfigurationClassBeanDefinitionReader {
 					// When clearly asking for Groovy, that's what they'll get...
 					readerClass = GroovyBeanDefinitionReader.class;
 				}
+				else if (shouldIgnoreXml) {
+					throw new UnsupportedOperationException("XML support disabled");
+				}
 				else {
 					// Primarily ".xml" files but for any other extension as well
 					readerClass = XmlBeanDefinitionReader.class;