Add registerErrorPageFilter option flag

Update SpringBootServletInitializer with a registerErrorPageFilter flag
that can be used to disable ErrorPageFilter registration.

Fixes gh-3603

spring-boot/src/main/java/org/springframework/boot/context/web/SpringBootServletInitializer.java

@@ -64,6 +64,18 @@ public abstract class SpringBootServletInitializer implements WebApplicationInit
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	private boolean registerErrorPageFilter = true;
+
+	/**
+	 * Set if the {@link ErrorPageFilter} should be registered. Set to {@code false} if
+	 * error page mappings should be handled via the Servlet container and not Spring
+	 * Boot.
+	 * @param registerErrorPageFilter if the {@link ErrorPageFilter} should be registered.
+	 */
+	protected final void setRegisterErrorPageFilter(boolean registerErrorPageFilter) {
+		this.registerErrorPageFilter = registerErrorPageFilter;
+	}
+
 	@Override
 	public void onStartup(ServletContext servletContext) throws ServletException {
 		WebApplicationContext rootAppContext = createRootApplicationContext(servletContext);
@@ -106,7 +118,9 @@ public abstract class SpringBootServletInitializer implements WebApplicationInit
 				"No SpringApplication sources have been defined. Either override the "
 						+ "configure method or add an @Configuration annotation");
 		// Ensure error pages are registered
+		if (this.registerErrorPageFilter) {
 			application.getSources().add(ErrorPageFilter.class);
+		}
 		return run(application);
 	}
 

spring-boot/src/test/java/org/springframework/boot/context/web/SpringBootServletInitializerTests.java

@@ -38,7 +38,7 @@ import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertThat;
 
 /**
- * Tests for {@link SpringBootServletInitializerTests}.
+ * Tests for {@link SpringBootServletInitializer}.
  *
  * @author Phillip Webb
  * @author Andy Wilkinson
@@ -75,8 +75,8 @@ public class SpringBootServletInitializerTests {
 				equalToSet(Config.class, ErrorPageFilter.class));
 	}
 
-	@SuppressWarnings("rawtypes")
 	@Test
+	@SuppressWarnings("rawtypes")
 	public void mainClassHasSensibleDefault() throws Exception {
 		new WithConfigurationAnnotation()
 				.createRootApplicationContext(this.servletContext);
@@ -86,6 +86,14 @@ public class SpringBootServletInitializerTests {
 				is(equalTo((Class) WithConfigurationAnnotation.class)));
 	}
 
+	@Test
+	public void withErrorPageFilterNotRegistered() throws Exception {
+		new WithErrorPageFilterNotRegistered()
+				.createRootApplicationContext(this.servletContext);
+		assertThat(this.application.getSources(),
+				equalToSet(WithErrorPageFilterNotRegistered.class));
+	}
+
 	private Matcher<? super Set<Object>> equalToSet(Object... items) {
 		Set<Object> set = new LinkedHashSet<Object>();
 		Collections.addAll(set, items);
@@ -115,6 +123,16 @@ public class SpringBootServletInitializerTests {
 
 	}
 
+	@Configuration
+	public class WithErrorPageFilterNotRegistered extends
+			MockSpringBootServletInitializer {
+
+		public WithErrorPageFilterNotRegistered() {
+			setRegisterErrorPageFilter(false);
+		}
+
+	}
+
 	@Configuration
 	public static class Config {