Update UserAgent header format

Author: nvasiu

sdk/src/main/java/software/amazon/lambda/durable/DurableConfig.java

@@ -72,7 +72,7 @@ public final class DurableConfig {
 
     private static final String VERSION_FILE = "/version.prop";
     private static final String PROJECT_VERSION = getProjectVersion(VERSION_FILE);
-    private static final String USER_AGENT_SUFFIX = "@aws/durable-execution-sdk-java/" + PROJECT_VERSION;
+    private static final String USER_AGENT_SUFFIX = "aws-durable-execution-sdk-java/" + PROJECT_VERSION;
 
     /**
      * A default ExecutorService for running user-defined operations. Uses a cached thread pool with daemon threads by

sdk/src/test/java/software/amazon/lambda/durable/DurableConfigTest.java

@@ -272,7 +272,7 @@ void testAddUserAgentSuffix_SetsUserAgentOnBuilder() {
         var userAgentSuffix = overrideConfig.advancedOption(SdkAdvancedClientOption.USER_AGENT_SUFFIX);
         assertTrue(userAgentSuffix.isPresent(), "USER_AGENT_SUFFIX should be set");
         assertTrue(
-                userAgentSuffix.get().contains("@aws/durable-execution-sdk-java/"),
+                userAgentSuffix.get().contains("aws-durable-execution-sdk-java/"),
                 "User agent suffix should contain SDK identifier, got: " + userAgentSuffix.get());
     }
 
@@ -286,7 +286,7 @@ void testAddUserAgentSuffix_PreservesExistingConfiguration() {
         var overrideConfig = result.overrideConfiguration();
         var userAgentSuffix = overrideConfig.advancedOption(SdkAdvancedClientOption.USER_AGENT_SUFFIX);
         assertTrue(userAgentSuffix.isPresent());
-        assertTrue(userAgentSuffix.get().contains("@aws/durable-execution-sdk-java/"));
+        assertTrue(userAgentSuffix.get().contains("aws-durable-execution-sdk-java/"));
     }
 
     @Test