STruncate Observation Event Name

To make events easier for event repositories, remove
the rather common word Filter from the end of the filter-based
event names.

Closes spring-projectsgh-12811

web/src/main/java/org/springframework/security/web/ObservationFilterChainDecorator.java

@@ -145,6 +145,8 @@ static final class ObservationFilter implements Filter {
 
 		private final String name;
 
+		private final String eventName;
+
 		private final int position;
 
 		private final int size;
@@ -153,6 +155,12 @@ static final class ObservationFilter implements Filter {
 			this.registry = registry;
 			this.filter = filter;
 			this.name = filter.getClass().getSimpleName();
+			if (this.name.endsWith("Filter")) {
+				this.eventName = this.name.substring(0, this.name.lastIndexOf("Filter"));
+			}
+			else {
+				this.eventName = this.name;
+			}
 			this.position = position;
 			this.size = size;
 		}
@@ -181,15 +189,15 @@ private void wrapFilter(ServletRequest request, ServletResponse response, Filter
 				parentBefore.setFilterName(this.name);
 				parentBefore.setChainPosition(this.position);
 			}
-			parent.before().event(Observation.Event.of(this.name + ".before", "before " + this.name));
+			parent.before().event(Observation.Event.of(this.eventName + ".before", "before " + this.eventName));
 			this.filter.doFilter(request, response, chain);
 			parent.start();
 			if (parent.after().getContext() instanceof FilterChainObservationContext parentAfter) {
 				parentAfter.setChainSize(this.size);
 				parentAfter.setFilterName(this.name);
 				parentAfter.setChainPosition(this.size - this.position + 1);
 			}
-			parent.after().event(Observation.Event.of(this.name + ".after", "after " + this.name));
+			parent.after().event(Observation.Event.of(this.eventName + ".after", "after " + this.eventName));
 		}
 
 		private AroundFilterObservation parent(HttpServletRequest request) {

web/src/test/java/org/springframework/security/web/ObservationFilterChainDecoratorTests.java

@@ -16,13 +16,17 @@
 
 package org.springframework.security.web;
 
+import java.io.IOException;
 import java.util.List;
 
 import io.micrometer.observation.Observation;
 import io.micrometer.observation.ObservationHandler;
 import io.micrometer.observation.ObservationRegistry;
 import jakarta.servlet.Filter;
 import jakarta.servlet.FilterChain;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.ServletRequest;
+import jakarta.servlet.ServletResponse;
 import org.junit.jupiter.api.Test;
 import org.mockito.ArgumentCaptor;
 
@@ -87,4 +91,32 @@ void decorateFiltersWhenDefaultsThenObserves() throws Exception {
 		assertThat(events.get(1).getName()).isEqualTo(filter.getClass().getSimpleName() + ".after");
 	}
 
+	@Test
+	void eventNameWhenEndsInFilterThenTruncates() throws Exception {
+		ObservationHandler<?> handler = mock(ObservationHandler.class);
+		given(handler.supportsContext(any())).willReturn(true);
+		ObservationRegistry registry = ObservationRegistry.create();
+		registry.observationConfig().observationHandler(handler);
+		ObservationFilterChainDecorator decorator = new ObservationFilterChainDecorator(registry);
+		FilterChain chain = mock(FilterChain.class);
+		Filter filter = new MyTestFilter();
+		FilterChain decorated = decorator.decorate(chain, List.of(filter));
+		decorated.doFilter(new MockHttpServletRequest("GET", "/"), new MockHttpServletResponse());
+		verify(handler, times(2)).onStart(any());
+		ArgumentCaptor<Observation.Event> event = ArgumentCaptor.forClass(Observation.Event.class);
+		verify(handler, times(2)).onEvent(event.capture(), any());
+		List<Observation.Event> events = event.getAllValues();
+		assertThat(events.get(0).getName()).isEqualTo("MyTest.before");
+		assertThat(events.get(1).getName()).isEqualTo("MyTest.after");
+	}
+
+	private static class MyTestFilter implements Filter {
+
+		@Override
+		public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
+				throws IOException, ServletException {
+		}
+
+	}
+
 }