fix(tracing): align ErrorType mapping with updated specification

- Removed heuristic exception mappings for CLIENT_REDIRECT_ERROR and CLIENT_UNKNOWN_ERROR to fall back to simple class name
- Refined mapping for CLIENT_AUTHENTICATION_ERROR by removing FileNotFoundException
- Added unmapped placeholders to ErrorType enum
- Updated unit and integration tests to verify new fallback mechanisms

Author: diegomarquezp

gax-java/gax/src/main/java/com/google/api/gax/tracing/ErrorTypeUtil.java

@@ -34,7 +34,6 @@
 import com.google.api.gax.rpc.WatchdogTimeoutException;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableSet;
-import java.io.FileNotFoundException;
 import java.net.BindException;
 import java.net.ConnectException;
 import java.net.NoRouteToHostException;
@@ -52,10 +51,14 @@ public enum ErrorType {
     CLIENT_TIMEOUT,
     CLIENT_CONNECTION_ERROR,
     CLIENT_REQUEST_ERROR,
+    /** Placeholder for potential future request body errors. */
     CLIENT_REQUEST_BODY_ERROR,
+    /** Placeholder for potential future response decode errors. */
     CLIENT_RESPONSE_DECODE_ERROR,
+    /** Placeholder for potential future redirect errors. */
     CLIENT_REDIRECT_ERROR,
     CLIENT_AUTHENTICATION_ERROR,
+    /** Placeholder for potential future unknown errors. */
     CLIENT_UNKNOWN_ERROR,
     INTERNAL;
 
@@ -66,7 +69,7 @@ public String toString() {
   }
 
   private static final Set<Class<? extends Throwable>> AUTHENTICATION_EXCEPTION_CLASSES =
-      ImmutableSet.of(GeneralSecurityException.class, FileNotFoundException.class);
+      ImmutableSet.of(GeneralSecurityException.class);
 
   private static final Set<Class<? extends Throwable>> CLIENT_TIMEOUT_EXCEPTION_CLASSES =
       ImmutableSet.of(
@@ -193,16 +196,10 @@ private static String getClientSideError(Throwable error) {
     if (isClientAuthenticationError(error)) {
       return ErrorType.CLIENT_AUTHENTICATION_ERROR.toString();
     }
-    if (isClientRedirectError(error)) {
-      return ErrorType.CLIENT_REDIRECT_ERROR.toString();
-    }
     // This covers CLIENT_REQUEST_ERROR for general illegal arguments in client requests.
     if (error instanceof IllegalArgumentException) {
       return ErrorType.CLIENT_REQUEST_ERROR.toString();
     }
-    if (isClientUnknownError(error)) {
-      return ErrorType.CLIENT_UNKNOWN_ERROR.toString();
-    }
     return null;
   }
 
@@ -228,40 +225,10 @@ private static boolean isClientConnectionError(Throwable e) {
     return hasErrorClassInCauseChain(e, CLIENT_CONNECTION_EXCEPTIONS);
   }
 
-  /**
-   * Checks if the given Throwable represents a client-side redirect error. This is identified by
-   * the presence of "redirect" in the exception message.
-   *
-   * @param e The Throwable to check.
-   * @return true if the error is a client redirect error, false otherwise.
-   */
-  private static boolean isClientRedirectError(Throwable e) {
-    return e.getMessage() != null && e.getMessage().contains("redirect");
-  }
-
-  /**
-   * Checks if the given Throwable represents a client-side authentication error. This is identified
-   * by exceptions related to the auth library.
-   *
-   * @param e The Throwable to check.
-   * @return true if the error is a client authentication error, false otherwise.
-   */
   private static boolean isClientAuthenticationError(Throwable e) {
     return hasErrorClassInCauseChain(e, AUTHENTICATION_EXCEPTION_CLASSES);
   }
 
-  /**
-   * Checks if the given Throwable represents an unknown client-side error. This is a general
-   * fallback for exceptions whose class name contains "unknown", indicating an unclassified
-   * client-side issue.
-   *
-   * @param e The Throwable to check.
-   * @return true if the error is an unknown client error, false otherwise.
-   */
-  private static boolean isClientUnknownError(Throwable e) {
-    return e.getClass().getName().toLowerCase().contains("unknown");
-  }
-
   /**
    * Recursively checks the throwable and its cause chain for any of the specified error classes.
    *

gax-java/gax/src/test/java/com/google/api/gax/rpc/ErrorTypeUtilTest.java

@@ -33,7 +33,6 @@
 
 import com.google.api.gax.rpc.testing.FakeStatusCode;
 import com.google.api.gax.tracing.ErrorTypeUtil;
-import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.net.BindException;
 import java.net.ConnectException;
@@ -113,7 +112,8 @@ void testExtractErrorType_realUnknownHostException() {
   void testExtractErrorType_realSSLHandshakeException() throws Exception {
     // Emulating a reliable SSLHandshakeException (vs a generic SSLException) requires
     // complex keystore setups which are brittle. We instantiate it directly here.
-    assertThat(ErrorTypeUtil.extractErrorType(new SSLHandshakeException("Cert path building failed")))
+    assertThat(
+            ErrorTypeUtil.extractErrorType(new SSLHandshakeException("Cert path building failed")))
         .isEqualTo(ErrorTypeUtil.ErrorType.CLIENT_CONNECTION_ERROR.toString());
   }
 
@@ -135,16 +135,17 @@ void testExtractErrorType_realBindException() throws Exception {
   void testExtractErrorType_clientTimeout_others() {
     assertThat(ErrorTypeUtil.extractErrorType(new WatchdogTimeoutException("timeout", false)))
         .isEqualTo(ErrorTypeUtil.ErrorType.CLIENT_TIMEOUT.toString());
-    assertThat(ErrorTypeUtil.extractErrorType(new DeadlineExceededException("timeout", null, new FakeStatusCode(StatusCode.Code.DEADLINE_EXCEEDED), false)))
+    assertThat(
+            ErrorTypeUtil.extractErrorType(
+                new DeadlineExceededException(
+                    "timeout", null, new FakeStatusCode(StatusCode.Code.DEADLINE_EXCEEDED), false)))
         .isEqualTo(ErrorTypeUtil.ErrorType.CLIENT_TIMEOUT.toString());
   }
 
   @Test
   void testExtractErrorType_clientAuthenticationError() {
     assertThat(ErrorTypeUtil.extractErrorType(new GeneralSecurityException("auth fail")))
         .isEqualTo(ErrorTypeUtil.ErrorType.CLIENT_AUTHENTICATION_ERROR.toString());
-    assertThat(ErrorTypeUtil.extractErrorType(new FileNotFoundException("key not found")))
-        .isEqualTo(ErrorTypeUtil.ErrorType.CLIENT_AUTHENTICATION_ERROR.toString());
   }
 
   @Test
@@ -177,7 +178,19 @@ void testExtractErrorType_causeChainTraversal() {
 
   @Test
   void testExtractErrorType_unknownException() {
-      assertThat(ErrorTypeUtil.extractErrorType(new Exception("Unknown stuff")))
-          .isEqualTo("Exception");
+    assertThat(ErrorTypeUtil.extractErrorType(new Exception("Unknown stuff")))
+        .isEqualTo("Exception");
+  }
+
+  @Test
+  void testExtractErrorType_redirectFallback() {
+    assertThat(ErrorTypeUtil.extractErrorType(new Exception("redirect"))).isEqualTo("Exception");
+  }
+
+  @Test
+  void testExtractErrorType_unknownClassNameFallback() {
+    class UnknownClientException extends Exception {}
+    assertThat(ErrorTypeUtil.extractErrorType(new UnknownClientException()))
+        .isEqualTo("UnknownClientException");
   }
 }

gax-java/gax/src/test/java/com/google/api/gax/tracing/SpanTracerTest.java

@@ -218,9 +218,7 @@ void testAttemptFailed_clientRedirectError() {
     tracer.attemptFailedRetriesExhausted(new RedirectException("redirect failed"));
 
     verify(attemptHandle)
-        .addAttribute(
-            ObservabilityAttributes.ERROR_TYPE_ATTRIBUTE,
-            ErrorTypeUtil.ErrorType.CLIENT_REDIRECT_ERROR.toString());
+        .addAttribute(ObservabilityAttributes.ERROR_TYPE_ATTRIBUTE, "RedirectException");
     verify(attemptHandle).end();
   }
 
@@ -248,9 +246,7 @@ void testAttemptFailed_clientUnknownError() {
     tracer.attemptFailedRetriesExhausted(new UnknownClientException());
 
     verify(attemptHandle)
-        .addAttribute(
-            ObservabilityAttributes.ERROR_TYPE_ATTRIBUTE,
-            ErrorTypeUtil.ErrorType.CLIENT_UNKNOWN_ERROR.toString());
+        .addAttribute(ObservabilityAttributes.ERROR_TYPE_ATTRIBUTE, "UnknownClientException");
     verify(attemptHandle).end();
   }
 

java-showcase/gapic-showcase/src/test/java/com/google/showcase/v1beta1/it/ITOtelErrorType.java

@@ -34,6 +34,7 @@
 import static org.junit.Assert.assertThrows;
 
 import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.api.gax.httpjson.RestSerializationException;
 import com.google.api.gax.rpc.DeadlineExceededException;
 import com.google.api.gax.rpc.StatusCode.Code;
 import com.google.api.gax.rpc.UnavailableException;
@@ -383,7 +384,9 @@ void testTracing_clientAuthenticationError_GeneralSecurityException_grpc() throw
   void testTracing_clientAuthenticationError_FileNotFoundException_grpc() throws Exception {
     try (EchoClient client = createInterceptorClient(new FileNotFoundException("Key not found"))) {
       assertThrows(RuntimeException.class, () -> client.echo(EchoRequest.newBuilder().setContent("test").build()));
-      verifyErrorTypeAttribute("CLIENT_AUTHENTICATION_ERROR");
+      // Wrapping non-RuntimeExceptions in RuntimeException during interceptCall()
+      // means the simple class name of the exception being recorded is "RuntimeException"
+      verifyErrorTypeAttribute("RuntimeException");
     }
   }
 
@@ -399,7 +402,9 @@ void testTracing_clientRequestError_IllegalArgumentException_grpc() throws Excep
   void testTracing_clientRedirectError_grpc() throws Exception {
     try (EchoClient client = createInterceptorClient(new RuntimeException("Too many redirects"))) {
       assertThrows(RuntimeException.class, () -> client.echo(EchoRequest.newBuilder().setContent("test").build()));
-      verifyErrorTypeAttribute("CLIENT_REDIRECT_ERROR");
+      // Heuristic mapping of "redirect" in message has been removed.
+      // Expected result is now the simple class name of the exception.
+      verifyErrorTypeAttribute("RuntimeException");
     }
   }
 
@@ -409,7 +414,19 @@ void testTracing_clientUnknownError_grpc() throws Exception {
     class MyUnknownException extends RuntimeException {}
     try (EchoClient client = createInterceptorClient(new MyUnknownException())) {
       assertThrows(RuntimeException.class, () -> client.echo(EchoRequest.newBuilder().setContent("test").build()));
-      verifyErrorTypeAttribute("CLIENT_UNKNOWN_ERROR");
+      // Heuristic mapping of "Unknown" in class name has been removed.
+      // Expected result is now the simple class name of the exception.
+      verifyErrorTypeAttribute("MyUnknownException");
+    }
+  }
+
+  @Test
+  void testTracing_clientRequestError_RestSerializationException_httpjson() throws Exception {
+    try (EchoClient client = createInterceptorClient(new RestSerializationException("failed to serialize", null))) {
+      assertThrows(RuntimeException.class, () -> client.echo(EchoRequest.newBuilder().setContent("test").build()));
+      // RestSerializationException is not handled due to ambiguity (serialization vs deserialization).
+      // Expected result is now its simple class name.
+      verifyErrorTypeAttribute("RestSerializationException");
     }
   }
 }