GH-332 - Avoid proxying configuration classes for observability purposes.

We now skip configuration classes for observability-related proxying as it's hard to detect those during the ProxyFactory setup to configure target class proxying. Also, configuration classes are usually no targets of inter-module communication and thus don't need to be observed at all.

spring-modulith-observability/src/test/java/example/sample/SampleConfiguration.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package example.sample;
+
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * @author Oliver Drotbohm
+ */
+@Configuration
+public class SampleConfiguration {}