Document that @⁠MockitoSpyBean cannot spy on a scoped proxy

See gh-35722

Author: sbrannen

framework-docs/modules/ROOT/pages/testing/annotations/integration-spring/annotation-mockitobean.adoc

@@ -102,6 +102,10 @@ will be replaced with a singleton mock of the type of object created by the `Fac
 
 Similarly, when using `@MockitoSpyBean` to create a spy for a `FactoryBean`, a spy will
 be created for the object created by the `FactoryBean`, not for the `FactoryBean` itself.
+
+Furthermore, `@MockitoSpyBean` cannot be used to spy on a scoped proxy — for example, a
+bean annotated with `@Scope(proxyMode = ScopedProxyMode.TARGET_CLASS)`. Any attempt to do
+so will fail with an exception.
 ====
 
 [NOTE]

spring-test/src/main/java/org/springframework/test/context/bean/override/mockito/MockitoSpyBean.java

@@ -94,6 +94,12 @@
  * be created for the object created by the {@code FactoryBean}, not for the
  * {@code FactoryBean} itself.
  *
+ * <p><strong>WARNING</strong>: {@code @MockitoSpyBean} cannot be used to spy on
+ * a scoped proxy &mdash; for example, a bean annotated with
+ * {@link org.springframework.context.annotation.Scope
+ * &#64;Scope(proxyMode = ScopedProxyMode.TARGET_CLASS)}. Any attempt to do so will
+ * fail with an exception.
+ *
  * <p>There are no restrictions on the visibility of a {@code @MockitoSpyBean} field.
  * Such fields can therefore be {@code public}, {@code protected}, package-private
  * (default visibility), or {@code private} depending on the needs or coding