Cover deserialization failure

Author: schnapster

oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/jackson2/OAuth2AuthenticationExceptionMixinTests.java

@@ -71,6 +71,15 @@ public void serializeWhenRequiredAttributesOnlyThenSerializes() throws JsonProce
 		JSONAssert.assertEquals(expected, serializedJson, true);
 	}
 
+	@Test
+	public void deserializeWhenMixinNotRegisteredThenThrowJsonProcessingException() {
+		String json = asJson(new OAuth2AuthenticationException(
+				new OAuth2Error("[authorization_request_not_found] ")
+		));
+		assertThatThrownBy(() -> new ObjectMapper().readValue(json, OAuth2AuthorizationRequest.class))
+				.isInstanceOf(JsonProcessingException.class);
+	}
+
 	@Test
 	public void deserializeWhenMixinRegisteredThenDeserializes() throws IOException {
 		OAuth2AuthenticationException expected = new OAuth2AuthenticationException(new OAuth2Error(