Register ApplicationContext bean with class (#584)

* Register ApplicationContext bean with class

* Assert none of the beans' types are null

* Fix typo

* Refactor to use Micronaut application context

* Use correct method to retrieve all bean defs

spring-boot-starter/src/main/java/io/micronaut/spring/boot/starter/MicronautImportRegistrar.java

@@ -130,6 +130,7 @@ public void registerBeanDefinitions(
         ppd.setBeanClass(MicronautPostProcess.class);
         ppd.setInstanceSupplier(() -> new MicronautPostProcess(context));
         registry.registerBeanDefinition("micronautPostProcess", ppd);
+        genericBeanDefinition.setBeanClass(context.getClass());
         genericBeanDefinition.setInstanceSupplier(() -> context);
         genericBeanDefinition.setDestroyMethodName("stop");
         registry.registerBeanDefinition(

spring-boot-starter/src/test/java/io/micronaut/spring/boot/starter/EnableMicronautTest.java

@@ -1,6 +1,8 @@
 package io.micronaut.spring.boot.starter;
 
+import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 
 import io.micronaut.context.ApplicationContext;
 import io.micronaut.context.annotation.Bean;
@@ -15,6 +17,7 @@
 import org.springframework.core.env.Environment;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -51,6 +54,12 @@ void testEnableMicronaut() {
         assertEquals("default", fooBean.getConfiguration().getName());
         assertEquals(3, fooBeanList.size());
         assertTrue(context.isRunning());
+        assertFalse(
+            context.getAllBeanDefinitions()
+                   .stream()
+                   .map(bean -> bean.getBeanType())
+                   .anyMatch(Objects::isNull)
+        );
     }
 }