Polish observability changes

Closes gh-29235

spring-web/src/main/java/org/springframework/http/client/observation/ClientHttpObservation.java

@@ -56,7 +56,7 @@ public enum ClientHttpObservation implements DocumentedObservation {
 	public enum LowCardinalityKeyNames implements KeyName {
 
 		/**
-		 * Name of HTTP request method or {@code "None"} if the request could not be created.
+		 * Name of HTTP request method or {@code "none"} if the request could not be created.
 		 */
 		METHOD {
 			@Override
@@ -67,7 +67,7 @@ public enum ClientHttpObservation implements DocumentedObservation {
 		},
 
 		/**
-		 * URI template used for HTTP request, or {@code ""} if none was provided.
+		 * URI template used for HTTP request, or {@code "none"} if none was provided.
 		 */
 		URI {
 			@Override
@@ -88,7 +88,7 @@ public enum ClientHttpObservation implements DocumentedObservation {
 		},
 
 		/**
-		 * Name of the exception thrown during the exchange, or {@code "None"} if no exception happened.
+		 * Name of the exception thrown during the exchange, or {@code "none"} if no exception happened.
 		 */
 		EXCEPTION {
 			@Override

spring-web/src/main/java/org/springframework/http/client/observation/DefaultClientHttpObservationConvention.java

@@ -23,7 +23,6 @@ import io.micrometer.common.KeyValues;
 
 import org.springframework.http.client.ClientHttpResponse;
 import org.springframework.http.observation.HttpOutcome;
-import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
 /**
@@ -41,10 +40,16 @@ public class DefaultClientHttpObservationConvention implements ClientHttpObserva
 
 	private static final KeyValue METHOD_NONE = KeyValue.of(ClientHttpObservation.LowCardinalityKeyNames.METHOD, "none");
 
+	private static final KeyValue STATUS_IO_ERROR = KeyValue.of(ClientHttpObservation.LowCardinalityKeyNames.STATUS, "IO_ERROR");
+
+	private static final KeyValue STATUS_CLIENT_ERROR = KeyValue.of(ClientHttpObservation.LowCardinalityKeyNames.STATUS, "CLIENT_ERROR");
+
 	private static final KeyValue EXCEPTION_NONE = KeyValue.of(ClientHttpObservation.LowCardinalityKeyNames.EXCEPTION, "none");
 
 	private static final KeyValue URI_EXPANDED_NONE = KeyValue.of(ClientHttpObservation.HighCardinalityKeyNames.URI_EXPANDED, "none");
 
+	private static final KeyValue CLIENT_NAME_NONE = KeyValue.of(ClientHttpObservation.HighCardinalityKeyNames.CLIENT_NAME, "none");
+
 	private final String name;
 
 	/**
@@ -94,18 +99,15 @@ public class DefaultClientHttpObservationConvention implements ClientHttpObserva
 	}
 
 	protected KeyValue status(ClientHttpObservationContext context) {
-		return KeyValue.of(ClientHttpObservation.LowCardinalityKeyNames.STATUS, getStatusMessage(context.getResponse()));
-	}
-
-	private String getStatusMessage(@Nullable ClientHttpResponse response) {
+		ClientHttpResponse response = context.getResponse();
+		if (response == null) {
+			return STATUS_CLIENT_ERROR;
+		}
 		try {
-			if (response == null) {
-				return "CLIENT_ERROR";
-			}
-			return String.valueOf(response.getStatusCode().value());
+			return KeyValue.of(ClientHttpObservation.LowCardinalityKeyNames.STATUS, String.valueOf(response.getStatusCode().value()));
 		}
 		catch (IOException ex) {
-			return "IO_ERROR";
+			return STATUS_IO_ERROR;
 		}
 	}
 
@@ -118,14 +120,14 @@ public class DefaultClientHttpObservationConvention implements ClientHttpObserva
 	}
 
 	protected static KeyValue outcome(ClientHttpObservationContext context) {
-		try {
-			if (context.getResponse() != null) {
+		if (context.getResponse() != null) {
+			try {
 				HttpOutcome httpOutcome = HttpOutcome.forStatus(context.getResponse().getStatusCode());
 				return httpOutcome.asKeyValue();
 			}
-		}
-		catch (IOException ex) {
-			// Continue
+			catch (IOException ex) {
+				// Continue
+			}
 		}
 		return HttpOutcome.UNKNOWN.asKeyValue();
 	}
@@ -143,11 +145,10 @@ public class DefaultClientHttpObservationConvention implements ClientHttpObserva
 	}
 
 	protected KeyValue clientName(ClientHttpObservationContext context) {
-		String host = "none";
 		if (context.getCarrier() != null && context.getCarrier().getURI().getHost() != null) {
-			host = context.getCarrier().getURI().getHost();
+			return KeyValue.of(ClientHttpObservation.HighCardinalityKeyNames.CLIENT_NAME, context.getCarrier().getURI().getHost());
 		}
-		return KeyValue.of(ClientHttpObservation.HighCardinalityKeyNames.CLIENT_NAME, host);
+		return CLIENT_NAME_NONE;
 	}
 
 }

spring-web/src/main/java/org/springframework/http/observation/HttpOutcome.java

@@ -22,12 +22,12 @@ import org.springframework.http.HttpStatusCode;
 
 /**
  * The outcome of an HTTP request.
- * <p>Used as the {@code "outcome} {@link io.micrometer.common.KeyValue}
+ * <p>Used as the {@code "outcome"} {@link io.micrometer.common.KeyValue}
  * for HTTP {@link io.micrometer.observation.Observation observations}.
  *
  * @author Brian Clozel
  * @author Andy Wilkinson
- * @since 6.0.0
+ * @since 6.0
  */
 public enum HttpOutcome {
 

spring-web/src/main/java/org/springframework/web/client/RestOperations.java

@@ -653,7 +653,7 @@ public interface RestOperations {
 	 * Execute the HTTP method to the given URI template, preparing the request with the
 	 * {@link RequestCallback}, and reading the response with a {@link ResponseExtractor}.
 	 * <p>URI Template variables are expanded using the given URI variables, if any.
-	 * @param url the URL
+	 * @param uriTemplate the URI template
 	 * @param method the HTTP method (GET, POST, etc)
 	 * @param requestCallback object that prepares the request
 	 * @param responseExtractor object that extracts the return value from the response
@@ -661,7 +661,7 @@ public interface RestOperations {
 	 * @return an arbitrary object, as returned by the {@link ResponseExtractor}
 	 */
 	@Nullable
-	<T> T execute(String url, HttpMethod method, @Nullable RequestCallback requestCallback,
+	<T> T execute(String uriTemplate, HttpMethod method, @Nullable RequestCallback requestCallback,
 			@Nullable ResponseExtractor<T> responseExtractor, Object... uriVariables)
 			throws RestClientException;
 
@@ -669,7 +669,7 @@ public interface RestOperations {
 	 * Execute the HTTP method to the given URI template, preparing the request with the
 	 * {@link RequestCallback}, and reading the response with a {@link ResponseExtractor}.
 	 * <p>URI Template variables are expanded using the given URI variables map.
-	 * @param url the URL
+	 * @param uriTemplate the URI template
 	 * @param method the HTTP method (GET, POST, etc)
 	 * @param requestCallback object that prepares the request
 	 * @param responseExtractor object that extracts the return value from the response
@@ -677,7 +677,7 @@ public interface RestOperations {
 	 * @return an arbitrary object, as returned by the {@link ResponseExtractor}
 	 */
 	@Nullable
-	<T> T execute(String url, HttpMethod method, @Nullable RequestCallback requestCallback,
+	<T> T execute(String uriTemplate, HttpMethod method, @Nullable RequestCallback requestCallback,
 			@Nullable ResponseExtractor<T> responseExtractor, Map<String, ?> uriVariables)
 			throws RestClientException;
 

spring-web/src/main/java/org/springframework/web/client/RestTemplate.java

@@ -340,7 +340,7 @@ public class RestTemplate extends InterceptingHttpAccessor implements RestOperat
 
 	/**
 	 * Configure an {@link ObservationRegistry} for collecting spans and metrics
-	 * for request execution. By default, {@link Observation} are No-Ops.
+	 * for request execution. By default, {@link Observation observations} are no-ops.
 	 * @param observationRegistry the observation registry to use
 	 * @since 6.0
 	 */
@@ -830,6 +830,7 @@ public class RestTemplate extends InterceptingHttpAccessor implements RestOperat
 	 * @param requestCallback object that prepares the request (can be {@code null})
 	 * @param responseExtractor object that extracts the return value from the response (can be {@code null})
 	 * @return an arbitrary object, as returned by the {@link ResponseExtractor}
+	 * @since 6.0
 	 */
 	@Nullable
 	@SuppressWarnings("try")

spring-web/src/main/java/org/springframework/web/observation/DefaultHttpRequestsObservationConvention.java

@@ -22,6 +22,7 @@ import io.micrometer.common.KeyValues;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.HttpStatusCode;
 import org.springframework.http.observation.HttpOutcome;
+import org.springframework.util.StringUtils;
 
 /**
  * Default {@link HttpRequestsObservationConvention}.
@@ -118,9 +119,12 @@ public class DefaultHttpRequestsObservationConvention implements HttpRequestsObs
 	}
 
 	protected KeyValue exception(HttpRequestsObservationContext context) {
-		return context.getError().map(throwable ->
-						KeyValue.of(HttpRequestsObservation.LowCardinalityKeyNames.EXCEPTION, throwable.getClass().getSimpleName()))
-				.orElse(EXCEPTION_NONE);
+		return context.getError().map(throwable -> {
+			String simpleName = throwable.getClass().getSimpleName();
+			return KeyValue.of(HttpRequestsObservation.LowCardinalityKeyNames.EXCEPTION,
+					StringUtils.hasText(simpleName) ? simpleName : throwable.getClass().getName());
+		})
+		.orElse(EXCEPTION_NONE);
 	}
 
 	protected KeyValue outcome(HttpRequestsObservationContext context) {

spring-web/src/main/java/org/springframework/web/observation/HttpRequestsObservation.java

@@ -54,7 +54,7 @@ public enum HttpRequestsObservation implements DocumentedObservation {
 	public enum LowCardinalityKeyNames implements KeyName {
 
 		/**
-		 * Name of HTTP request method or {@code "None"} if the request was not received properly.
+		 * Name of HTTP request method or {@code "none"} if the request was not received properly.
 		 */
 		METHOD {
 			@Override
@@ -65,7 +65,7 @@ public enum HttpRequestsObservation implements DocumentedObservation {
 		},
 
 		/**
-		 * HTTP response raw status code, or {@code "STATUS_UNKNOWN"} if no response was created.
+		 * HTTP response raw status code, or {@code "UNKNOWN"} if no response was created.
 		 */
 		STATUS {
 			@Override
@@ -87,7 +87,7 @@ public enum HttpRequestsObservation implements DocumentedObservation {
 		},
 
 		/**
-		 * Name of the exception thrown during the exchange, or {@code "None"} if no exception happened.
+		 * Name of the exception thrown during the exchange, or {@code "none"} if no exception happened.
 		 */
 		EXCEPTION {
 			@Override

spring-web/src/main/java/org/springframework/web/observation/HttpRequestsObservationContext.java

@@ -36,8 +36,8 @@ public class HttpRequestsObservationContext extends RequestReplyReceiverContext<
 
 	public HttpRequestsObservationContext(HttpServletRequest request, HttpServletResponse response) {
 		super(HttpServletRequest::getHeader);
-		this.setCarrier(request);
-		this.setResponse(response);
+		setCarrier(request);
+		setResponse(response);
 	}
 
 	@Nullable

spring-web/src/main/java/org/springframework/web/observation/HttpRequestsObservationFilter.java

@@ -37,7 +37,7 @@ import org.springframework.web.filter.OncePerRequestFilter;
  * for HTTP exchanges. This collects information about the execution time and
  * information gathered from the {@link HttpRequestsObservationContext}.
  * <p>Web Frameworks can fetch the current {@link HttpRequestsObservationContext context}
- * as a {@link #CURRENT_OBSERVATION_ATTRIBUTE request attribute} and contribute
+ * as a {@link #CURRENT_OBSERVATION_CONTEXT_ATTRIBUTE request attribute} and contribute
  * additional information to it.
  * The configured {@link HttpRequestsObservationConvention} will use this context to collect
  * {@link io.micrometer.common.KeyValue metadata} and attach it to the observation.
@@ -61,17 +61,17 @@ public class HttpRequestsObservationFilter extends OncePerRequestFilter {
 	private final HttpRequestsObservationConvention observationConvention;
 
 	/**
-	 * Create a {@code HttpRequestsObservationFilter} that records observations
+	 * Create an {@code HttpRequestsObservationFilter} that records observations
 	 * against the given {@link ObservationRegistry}. The default
 	 * {@link DefaultHttpRequestsObservationConvention convention} will be used.
 	 * @param observationRegistry the registry to use for recording observations
 	 */
 	public HttpRequestsObservationFilter(ObservationRegistry observationRegistry) {
-		this(observationRegistry, new DefaultHttpRequestsObservationConvention());
+		this(observationRegistry, DEFAULT_OBSERVATION_CONVENTION);
 	}
 
 	/**
-	 * Create a {@code HttpRequestsObservationFilter} that records observations
+	 * Create an {@code HttpRequestsObservationFilter} that records observations
 	 * against the given {@link ObservationRegistry} with a custom convention.
 	 * @param observationRegistry the registry to use for recording observations
 	 * @param observationConvention the convention to use for all recorded observations

spring-web/src/main/java/org/springframework/web/observation/reactive/DefaultHttpRequestsObservationConvention.java

@@ -21,6 +21,7 @@ import io.micrometer.common.KeyValues;
 
 import org.springframework.http.HttpStatus;
 import org.springframework.http.observation.HttpOutcome;
+import org.springframework.util.StringUtils;
 import org.springframework.web.util.pattern.PathPattern;
 
 /**
@@ -92,6 +93,9 @@ public class DefaultHttpRequestsObservationConvention implements HttpRequestsObs
 	}
 
 	protected KeyValue status(HttpRequestsObservationContext context) {
+		if (context.isConnectionAborted()) {
+			return STATUS_UNKNOWN;
+		}
 		return (context.getResponse() != null) ? KeyValue.of(HttpRequestsObservation.LowCardinalityKeyNames.STATUS, Integer.toString(context.getResponse().getStatusCode().value())) : STATUS_UNKNOWN;
 	}
 
@@ -120,16 +124,19 @@ public class DefaultHttpRequestsObservationConvention implements HttpRequestsObs
 	}
 
 	protected KeyValue exception(HttpRequestsObservationContext context) {
-		return context.getError().map(throwable ->
-						KeyValue.of(HttpRequestsObservation.LowCardinalityKeyNames.EXCEPTION, throwable.getClass().getSimpleName()))
-				.orElse(EXCEPTION_NONE);
+		return context.getError().map(throwable -> {
+			String simpleName = throwable.getClass().getSimpleName();
+			return KeyValue.of(HttpRequestsObservation.LowCardinalityKeyNames.EXCEPTION,
+					StringUtils.hasText(simpleName) ? simpleName : throwable.getClass().getName());
+		})
+		.orElse(EXCEPTION_NONE);
 	}
 
 	protected KeyValue outcome(HttpRequestsObservationContext context) {
 		if (context.isConnectionAborted()) {
 			return HttpOutcome.UNKNOWN.asKeyValue();
 		}
-		else if (context.getResponse() != null) {
+		if (context.getResponse() != null) {
 			HttpOutcome httpOutcome = HttpOutcome.forStatus(context.getResponse().getStatusCode());
 			return httpOutcome.asKeyValue();
 		}

spring-web/src/main/java/org/springframework/web/observation/reactive/HttpRequestsObservation.java

@@ -23,7 +23,7 @@ import io.micrometer.observation.docs.DocumentedObservation;
 
 /**
  * Documented {@link io.micrometer.common.KeyValue KeyValues} for the HTTP server observations
- * for Servlet-based web applications.
+ * for reactive web applications.
  * <p>This class is used by automated tools to document KeyValues attached to the HTTP server observations.
  * @author Brian Clozel
  * @since 6.0
@@ -54,7 +54,7 @@ public enum HttpRequestsObservation implements DocumentedObservation {
 	public enum LowCardinalityKeyNames implements KeyName {
 
 		/**
-		 * Name of HTTP request method or {@code "None"} if the request was not received properly.
+		 * Name of HTTP request method or {@code "none"} if the request was not received properly.
 		 */
 		METHOD {
 			@Override
@@ -65,7 +65,7 @@ public enum HttpRequestsObservation implements DocumentedObservation {
 		},
 
 		/**
-		 * HTTP response raw status code, or {@code "STATUS_UNKNOWN"} if no response was created.
+		 * HTTP response raw status code, or {@code "UNKNOWN"} if no response was created.
 		 */
 		STATUS {
 			@Override
@@ -87,7 +87,7 @@ public enum HttpRequestsObservation implements DocumentedObservation {
 		},
 
 		/**
-		 * Name of the exception thrown during the exchange, or {@code "None"} if no exception happened.
+		 * Name of the exception thrown during the exchange, or {@code "none"} if no exception happened.
 		 */
 		EXCEPTION {
 			@Override

spring-web/src/main/java/org/springframework/web/observation/reactive/HttpRequestsObservationContext.java

@@ -40,8 +40,8 @@ public class HttpRequestsObservationContext extends RequestReplyReceiverContext<
 
 	public HttpRequestsObservationContext(ServerWebExchange exchange) {
 		super((request, key) -> request.getHeaders().getFirst(key));
-		this.setCarrier(exchange.getRequest());
-		this.setResponse(exchange.getResponse());
+		setCarrier(exchange.getRequest());
+		setResponse(exchange.getResponse());
 	}
 
 	/**
@@ -66,7 +66,7 @@ public class HttpRequestsObservationContext extends RequestReplyReceiverContext<
 
 	/**
 	 * Whether the current connection was aborted by the client, resulting
-	 * in a {@link reactor.core.publisher.SignalType#CANCEL cancel signal} on te reactive chain,
+	 * in a {@link reactor.core.publisher.SignalType#CANCEL cancel signal} on the reactive chain,
 	 * or an {@code AbortedException} when reading the request.
 	 * @return if the connection has been aborted
 	 */

spring-web/src/main/java/org/springframework/web/observation/reactive/HttpRequestsObservationWebFilter.java

@@ -60,17 +60,17 @@ public class HttpRequestsObservationWebFilter implements WebFilter {
 	private final HttpRequestsObservationConvention observationConvention;
 
 	/**
-	 * Create a {@code HttpRequestsObservationWebFilter} that records observations
+	 * Create an {@code HttpRequestsObservationWebFilter} that records observations
 	 * against the given {@link ObservationRegistry}. The default
 	 * {@link DefaultHttpRequestsObservationConvention convention} will be used.
 	 * @param observationRegistry the registry to use for recording observations
 	 */
 	public HttpRequestsObservationWebFilter(ObservationRegistry observationRegistry) {
-		this(observationRegistry, new DefaultHttpRequestsObservationConvention());
+		this(observationRegistry, DEFAULT_OBSERVATION_CONVENTION);
 	}
 
 	/**
-	 * Create a {@code HttpRequestsObservationWebFilter} that records observations
+	 * Create an {@code HttpRequestsObservationWebFilter} that records observations
 	 * against the given {@link ObservationRegistry} with a custom convention.
 	 * @param observationRegistry the registry to use for recording observations
 	 * @param observationConvention the convention to use for all recorded observations

spring-web/src/test/java/org/springframework/http/observation/HttpOutcomeTests.java

@@ -57,7 +57,7 @@ class HttpOutcomeTests {
 	}
 
 	@ParameterizedTest
-	@ValueSource(ints = {404, 404, 405})
+	@ValueSource(ints = {400, 404, 405})
 	void shouldResolveClientError(int code) {
 		HttpOutcome httpOutcome = HttpOutcome.forStatus(HttpStatusCode.valueOf(code));
 		assertThat(httpOutcome).isEqualTo(HttpOutcome.CLIENT_ERROR);

spring-web/src/test/java/org/springframework/web/client/RestTemplateObservationTests.java

@@ -19,7 +19,6 @@ package org.springframework.web.client;
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.net.URI;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 
@@ -27,7 +26,6 @@ import io.micrometer.observation.tck.TestObservationRegistry;
 import io.micrometer.observation.tck.TestObservationRegistryAssert;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-import org.mockito.BDDMockito;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpInputMessage;
@@ -43,6 +41,7 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.BDDMockito.given;
+import static org.mockito.BDDMockito.willThrow;
 import static org.mockito.Mockito.mock;
 import static org.springframework.http.HttpMethod.GET;
 
@@ -50,7 +49,7 @@ import static org.springframework.http.HttpMethod.GET;
  * Tests for the client HTTP observations with {@link RestTemplate}.
  * @author Brian Clozel
  */
-public class RestTemplateObservationTests {
+class RestTemplateObservationTests {
 
 
 	private final TestObservationRegistry observationRegistry = TestObservationRegistry.create();
@@ -102,7 +101,7 @@ public class RestTemplateObservationTests {
 
 
 	@Test
-	void executeAddsSucessAsOutcome() throws Exception {
+	void executeAddsSuccessAsOutcome() throws Exception {
 		mockSentRequest(GET, "https://example.org");
 		mockResponseStatus(HttpStatus.OK);
 		mockResponseBody("Hello World", MediaType.TEXT_PLAIN);
@@ -117,7 +116,7 @@ public class RestTemplateObservationTests {
 		String url = "https://example.org";
 		mockSentRequest(GET, url);
 		mockResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR);
-		BDDMockito.willThrow(new HttpServerErrorException(HttpStatus.INTERNAL_SERVER_ERROR))
+		willThrow(new HttpServerErrorException(HttpStatus.INTERNAL_SERVER_ERROR))
 				.given(errorHandler).handleError(new URI(url), GET, response);
 
 		assertThatExceptionOfType(HttpServerErrorException.class).isThrownBy(() ->
@@ -133,7 +132,7 @@ public class RestTemplateObservationTests {
 
 		given(converter.canRead(String.class, null)).willReturn(true);
 		MediaType supportedMediaType = new MediaType("test", "supported");
-		given(converter.getSupportedMediaTypes()).willReturn(Collections.singletonList(supportedMediaType));
+		given(converter.getSupportedMediaTypes()).willReturn(List.of(supportedMediaType));
 		MediaType other = new MediaType("test", "other");
 		mockResponseBody("Test Body", other);
 		given(converter.canRead(String.class, other)).willReturn(false);

spring-web/src/test/java/org/springframework/web/observation/HttpRequestsObservationFilterTests.java

@@ -34,7 +34,7 @@ import static org.assertj.core.api.Assertions.assertThatThrownBy;
  * Tests for {@link HttpRequestsObservationFilter}.
  * @author Brian Clozel
  */
-public class HttpRequestsObservationFilterTests {
+class HttpRequestsObservationFilterTests {
 
 	private final TestObservationRegistry observationRegistry = TestObservationRegistry.create();
 

spring-web/src/test/java/org/springframework/web/observation/reactive/DefaultHttpRequestsObservationConventionTests.java

@@ -135,7 +135,7 @@ class DefaultHttpRequestsObservationConventionTests {
 		exchange.getResponse().setRawStatusCode(200);
 
 		assertThat(this.convention.getLowCardinalityKeyValues(context)).hasSize(5)
-				.contains(KeyValue.of("method", "GET"), KeyValue.of("uri", "UNKNOWN"), KeyValue.of("status", "200"),
+				.contains(KeyValue.of("method", "GET"), KeyValue.of("uri", "UNKNOWN"), KeyValue.of("status", "UNKNOWN"),
 						KeyValue.of("exception", "none"), KeyValue.of("outcome", "UNKNOWN"));
 		assertThat(this.convention.getHighCardinalityKeyValues(context)).hasSize(1)
 				.contains(KeyValue.of("uri.expanded", "/test/resource"));

spring-web/src/test/java/org/springframework/web/observation/reactive/HttpRequestsObservationWebFilterTests.java

@@ -85,7 +85,7 @@ class HttpRequestsObservationWebFilterTests {
 		assertThatHttpObservation().hasLowCardinalityKeyValue("outcome", "UNKNOWN");
 	}
 
-	WebFilterChain createFilterChain(ThrowingConsumer<ServerWebExchange> exchangeConsumer) {
+	private WebFilterChain createFilterChain(ThrowingConsumer<ServerWebExchange> exchangeConsumer) {
 		return filterExchange -> {
 			try {
 				exchangeConsumer.accept(filterExchange);

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/ClientObservation.java

@@ -64,7 +64,7 @@ public enum ClientObservation implements DocumentedObservation {
 		},
 
 		/**
-		 * URI template used for HTTP request, or {@code ""} if none was provided.
+		 * URI template used for HTTP request, or {@code "none"} if none was provided.
 		 */
 		URI {
 			@Override

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultClientObservationConvention.java

@@ -22,6 +22,7 @@ import io.micrometer.common.KeyValue;
 import io.micrometer.common.KeyValues;
 import io.micrometer.observation.ObservationConvention;
 
+import org.springframework.http.client.observation.ClientHttpObservation;
 import org.springframework.http.observation.HttpOutcome;
 import org.springframework.util.StringUtils;
 
@@ -40,8 +41,15 @@ public class DefaultClientObservationConvention implements ClientObservationConv
 
 	private static final KeyValue METHOD_NONE = KeyValue.of(ClientObservation.LowCardinalityKeyNames.METHOD, "none");
 
+	private static final KeyValue STATUS_IO_ERROR = KeyValue.of(ClientHttpObservation.LowCardinalityKeyNames.STATUS, "IO_ERROR");
+
+	private static final KeyValue STATUS_CLIENT_ERROR = KeyValue.of(ClientHttpObservation.LowCardinalityKeyNames.STATUS, "CLIENT_ERROR");
+
 	private static final KeyValue EXCEPTION_NONE = KeyValue.of(ClientObservation.LowCardinalityKeyNames.EXCEPTION, "none");
 
+	private static final KeyValue URI_EXPANDED_NONE = KeyValue.of(ClientHttpObservation.HighCardinalityKeyNames.URI_EXPANDED, "none");
+
+	private static final KeyValue CLIENT_NAME_NONE = KeyValue.of(ClientHttpObservation.HighCardinalityKeyNames.CLIENT_NAME, "none");
 
 	private final String name;
 
@@ -93,17 +101,17 @@ public class DefaultClientObservationConvention implements ClientObservationConv
 	}
 
 	protected KeyValue status(ClientObservationContext context) {
-		return KeyValue.of(ClientObservation.LowCardinalityKeyNames.STATUS, getStatusMessage(context));
-	}
-
-	private String getStatusMessage(ClientObservationContext context) {
-		if (context.getResponse() != null) {
-			return String.valueOf(context.getResponse().statusCode().value());
+		if (context.isAborted()) {
+			return STATUS_CLIENT_ERROR;
 		}
-		if (context.getError().isPresent()) {
-			return (context.getError().get() instanceof IOException) ? "IO_ERROR" : "CLIENT_ERROR";
+		ClientResponse response = context.getResponse();
+		if (response != null) {
+			return KeyValue.of(ClientObservation.LowCardinalityKeyNames.STATUS, String.valueOf(response.statusCode().value()));
 		}
-		return "CLIENT_ERROR";
+		if (context.getError().isPresent() && context.getError().get() instanceof IOException) {
+			return STATUS_IO_ERROR;
+		}
+		return STATUS_CLIENT_ERROR;
 	}
 
 	protected KeyValue exception(ClientObservationContext context) {
@@ -114,11 +122,11 @@ public class DefaultClientObservationConvention implements ClientObservationConv
 		}).orElse(EXCEPTION_NONE);
 	}
 
-	protected static KeyValue outcome(ClientObservationContext context) {
+	protected KeyValue outcome(ClientObservationContext context) {
 		if (context.isAborted()) {
 			return HttpOutcome.UNKNOWN.asKeyValue();
 		}
-		else if (context.getResponse() != null) {
+		if (context.getResponse() != null) {
 			HttpOutcome httpOutcome = HttpOutcome.forStatus(context.getResponse().statusCode());
 			return httpOutcome.asKeyValue();
 		}
@@ -134,15 +142,14 @@ public class DefaultClientObservationConvention implements ClientObservationConv
 		if (context.getCarrier() != null) {
 			return KeyValue.of(ClientObservation.HighCardinalityKeyNames.URI_EXPANDED, context.getCarrier().url().toASCIIString());
 		}
-		return KeyValue.of(ClientObservation.HighCardinalityKeyNames.URI_EXPANDED, "none");
+		return URI_EXPANDED_NONE;
 	}
 
 	protected KeyValue clientName(ClientObservationContext context) {
-		String host = "none";
 		if (context.getCarrier() != null && context.getCarrier().url().getHost() != null) {
-			host = context.getCarrier().url().getHost();
+			return KeyValue.of(ClientObservation.HighCardinalityKeyNames.CLIENT_NAME, context.getCarrier().url().getHost());
 		}
-		return KeyValue.of(ClientObservation.HighCardinalityKeyNames.CLIENT_NAME, host);
+		return CLIENT_NAME_NONE;
 	}
 
 }

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/WebClient.java

@@ -26,7 +26,7 @@ import java.util.function.Function;
 import java.util.function.IntPredicate;
 import java.util.function.Predicate;
 
-import io.micrometer.observation.Observation;
+import io.micrometer.observation.ObservationConvention;
 import io.micrometer.observation.ObservationRegistry;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
@@ -346,7 +346,7 @@ public interface WebClient {
 		Builder observationRegistry(ObservationRegistry observationRegistry);
 
 		/**
-		 * Provide a {@link Observation.ObservationConvention} to use for collecting
+		 * Provide an {@link ObservationConvention} to use for collecting
 		 * metadata for the current observation. Will use {@link DefaultClientObservationConvention}
 		 * if none provided.
 		 * @param observationConvention the observation convention to use

spring-webflux/src/test/java/org/springframework/web/reactive/function/client/DefaultClientObservationConventionTests.java

@@ -34,7 +34,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class DefaultClientObservationConventionTests {
 
-	private DefaultClientObservationConvention observationConvention = new DefaultClientObservationConvention();
+	private final DefaultClientObservationConvention observationConvention = new DefaultClientObservationConvention();
 
 	@Test
 	void shouldHaveName() {

spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientObservationTests.java

@@ -39,19 +39,19 @@ import static org.mockito.Mockito.verifyNoMoreInteractions;
  * Tests for the {@link WebClient} {@link io.micrometer.observation.Observation observations}.
  * @author Brian Clozel
  */
-public class DefaultClientObservationTests {
+class WebClientObservationTests {
 
 
 	private final TestObservationRegistry observationRegistry = TestObservationRegistry.create();
 
-	private ExchangeFunction exchangeFunction = mock(ExchangeFunction.class);
+	private final ExchangeFunction exchangeFunction = mock(ExchangeFunction.class);
 
-	private ArgumentCaptor<ClientRequest> request = ArgumentCaptor.forClass(ClientRequest.class);
+	private final ArgumentCaptor<ClientRequest> request = ArgumentCaptor.forClass(ClientRequest.class);
 
 	private WebClient.Builder builder;
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 		ClientResponse mockResponse = mock(ClientResponse.class);
 		when(mockResponse.statusCode()).thenReturn(HttpStatus.OK);
 		when(mockResponse.bodyToMono(Void.class)).thenReturn(Mono.empty());