s2a: Correct type of exception thrown

s2a/src/main/java/io/grpc/s2a/internal/handshaker/ProtoUtil.java

@@ -27,7 +27,8 @@ final class ProtoUtil {
    *
    * @param tlsVersion the {@link TLSVersion} object to be converted.
    * @return a {@link String} representation of the TLS version.
-   * @throws AssertionError if the {@code tlsVersion} is not one of the supported TLS versions.
+   * @throws IllegalArgumentException if the {@code tlsVersion} is not one of
+   *     the supported TLS versions.
    */
   @VisibleForTesting
   static String convertTlsProtocolVersion(TLSVersion tlsVersion) {
@@ -41,7 +42,7 @@ static String convertTlsProtocolVersion(TLSVersion tlsVersion) {
       case TLS_VERSION_1_0:
         return "TLSv1";
       default:
-        throw new AssertionError(
+        throw new IllegalArgumentException(
             String.format("TLS version %d is not supported.", tlsVersion.getNumber()));
     }
   }

s2a/src/main/java/io/grpc/s2a/internal/handshaker/S2ATrustManager.java

@@ -120,10 +120,10 @@ private void checkPeerTrusted(X509Certificate[] chain, boolean isCheckingClientC
     SessionResp resp;
     try {
       resp = stub.send(reqBuilder.build());
-    } catch (IOException | InterruptedException e) {
-      if (e instanceof InterruptedException) {
-        Thread.currentThread().interrupt();
-      }
+    } catch (IOException e) {
+      throw new CertificateException("Failed to send request to S2A.", e);
+    } catch (InterruptedException e) {
+      Thread.currentThread().interrupt();
       throw new CertificateException("Failed to send request to S2A.", e);
     }
     if (resp.hasStatus() && resp.getStatus().getCode() != 0) {

s2a/src/main/java/io/grpc/s2a/internal/handshaker/SslContextFactory.java

@@ -63,7 +63,8 @@ static SslContext createForClient(
           KeyStoreException,
           NoSuchAlgorithmException,
           UnrecoverableKeyException,
-          GeneralSecurityException {
+          GeneralSecurityException,
+          IllegalArgumentException {
     checkNotNull(stub, "stub should not be null.");
     checkNotNull(targetName, "targetName should not be null on client side.");
     GetTlsConfigurationResp.ClientTlsConfiguration clientTlsConfiguration;
@@ -136,7 +137,8 @@ private static void configureSslContextWithClientTlsConfiguration(
           IOException,
           KeyStoreException,
           NoSuchAlgorithmException,
-          UnrecoverableKeyException {
+          UnrecoverableKeyException,
+          IllegalArgumentException {
     sslContextBuilder.keyManager(createKeylessManager(clientTlsConfiguration));
     ImmutableSet<String> tlsVersions =
         ProtoUtil.buildTlsProtocolVersionSet(

s2a/src/test/java/io/grpc/s2a/internal/handshaker/ProtoUtilTest.java

@@ -46,9 +46,9 @@ public void convertTlsProtocolVersion_success() {
 
   @Test
   public void convertTlsProtocolVersion_withUnknownTlsVersion_fails() {
-    AssertionError expected =
+    IllegalArgumentException expected =
         assertThrows(
-            AssertionError.class,
+            IllegalArgumentException.class,
             () -> ProtoUtil.convertTlsProtocolVersion(TLSVersion.TLS_VERSION_UNSPECIFIED));
     expect.that(expected).hasMessageThat().isEqualTo("TLS version 0 is not supported.");
   }
@@ -79,9 +79,9 @@ public void buildTlsProtocolVersionSet_success() {
 
   @Test
   public void buildTlsProtocolVersionSet_failure() {
-    AssertionError expected =
+    IllegalArgumentException expected =
         assertThrows(
-            AssertionError.class,
+            IllegalArgumentException.class,
             () ->
                 ProtoUtil.buildTlsProtocolVersionSet(
                     TLSVersion.TLS_VERSION_UNSPECIFIED, TLSVersion.TLS_VERSION_1_3));