[bs-73] Tweak algorithm for detecting anonymous classes

@Bean definitions in Groovy that contain closures have the bean name in
the class name.  Ugh.  Added regex match to catch that.

[#48718891]

spring-bootstrap/src/main/java/org/springframework/bootstrap/BeanDefinitionLoader.java

@@ -163,7 +163,7 @@ class BeanDefinitionLoader {
 		}
 		// Nested anonymous classes are not eligible for registration, nor are groovy
 		// closures
-		if (type.isAnonymousClass() || type.getName().contains("$_closure")
+		if (type.isAnonymousClass() || type.getName().matches(".*\\$_.*closure.*")
 				|| type.getConstructors() == null || type.getConstructors().length == 0) {
 			return false;
 		}