test(kafka-connect): use generic assertion message in KafkaConnectApiFactoryTest

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 2 people

providers/jikkou-provider-kafka-connect/src/test/java/io/jikkou/kafka/connect/api/KafkaConnectApiFactoryTest.java

@@ -64,6 +64,6 @@ void shouldBuildBasicAuthHeaderFromActualCredentials() throws InterruptedExcepti
                 .encodeToString("alice:secret".getBytes(StandardCharsets.UTF_8));
         // result should correspond to base64 encoded string "alice:secret" prefixed with "Basic"
         Assertions.assertEquals("Basic " + expectedCredentials, authorization,
-                "Authorization header must encode the actual credentials, not the Supplier toString()");
+                "Authorization header must contain the base64-encoded credentials");
     }
 }