Fix double registration of Filter

A stupid typo lurking in EmbeddedWebApplicationContext meant
that a FilterRegistrationBean would register a Filter, and then
it would be registered again without the initializer.

[Fixes #54676948] Filter registered twice

spring-boot/src/main/java/org/springframework/boot/context/embedded/EmbeddedWebApplicationContext.java

@@ -241,7 +241,7 @@ public class EmbeddedWebApplicationContext extends GenericWebApplicationContext
 		for (Entry<String, Filter> filterBean : getOrderedBeansOfType(Filter.class)) {
 			String name = filterBean.getKey();
 			Filter filter = filterBean.getValue();
-			if (!servletRegistrations.contains(filter)) {
+			if (!filterRegistrations.contains(filter)) {
 				FilterRegistrationBean registration = new FilterRegistrationBean(filter);
 				registration.setName(name);
 				initializers.add(registration);

spring-boot/src/test/java/org/springframework/boot/context/embedded/EmbeddedWebApplicationContextTests.java

@@ -317,6 +317,20 @@ public class EmbeddedWebApplicationContextTests {
 		verify(servletContext, atMost(1)).addFilter(anyString(), (Filter) anyObject());
 	}
 
+	@Test
+	public void filterReegistrationBeansSkipsRegisteredFilters() throws Exception {
+		addEmbeddedServletContainerFactoryBean();
+		Filter filter = mock(Filter.class);
+		FilterRegistrationBean initializer = new FilterRegistrationBean(filter);
+		this.context.registerBeanDefinition("initializerBean",
+				beanDefinition(initializer));
+		this.context.registerBeanDefinition("filterBean", beanDefinition(filter));
+		this.context.refresh();
+		ServletContext servletContext = getEmbeddedServletContainerFactory()
+				.getServletContext();
+		verify(servletContext, atMost(1)).addFilter(anyString(), (Filter) anyObject());
+	}
+
 	@Test
 	public void postProcessEmbeddedServletContainerFactory() throws Exception {
 		RootBeanDefinition bd = new RootBeanDefinition(

spring-boot/src/test/java/org/springframework/boot/context/embedded/tomcat/TomcatEmbeddedServletContainerFactoryTests.java

@@ -38,6 +38,7 @@ import static org.mockito.Mockito.mock;
  * {@link TomcatEmbeddedServletContainer}.
  * 
  * @author Phillip Webb
+ * @author Dave Syer
  */
 public class TomcatEmbeddedServletContainerFactoryTests extends
 		AbstractEmbeddedServletContainerFactoryTests {