Fix ResolvableType raw class isAssignable checks (backport from 5.1.x)

Closes gh-23321

spring-core/src/main/java/org/springframework/core/ResolvableType.java

@@ -991,7 +991,7 @@ public class ResolvableType implements Serializable {
 			}
 			@Override
 			public boolean isAssignableFrom(ResolvableType other) {
-				Class<?> otherClass = other.getRawClass();
+				Class<?> otherClass = other.resolve();
 				return (otherClass != null && (clazz == null || ClassUtils.isAssignable(clazz, otherClass)));
 			}
 		};