fix: improve websocket message (#4019)

Signed-off-by: Pablo Carle <pablo.carle@broadcom.com>
Co-authored-by: Pablo Carle <pablo.carle@broadcom.com>

Author: pablocarle

gateway-service/src/main/java/org/zowe/apiml/gateway/websocket/ApimlWebSocketSession.java

@@ -45,6 +45,6 @@ public void onError(Throwable ex) {
         if (ex.getCause() instanceof AuthenticationException) {
             close(new CloseStatus(1003, "Invalid login credentials"));
         }
-        close(CloseStatus.SERVER_ERROR);
+        close(CloseStatus.create(CloseStatus.SERVER_ERROR.getCode(), ex.getMessage()));
     }
 }

gateway-service/src/test/java/org/zowe/apiml/gateway/websocket/ApimlWebSocketSessionTest.java

@@ -22,6 +22,7 @@
 import reactor.core.publisher.Sinks;
 
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.argThat;
 import static org.mockito.Mockito.doCallRealMethod;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.times;
@@ -52,7 +53,7 @@ void givenAuthenticationException_WhenError_then1003() {
     @Test
     void givenGenericException_WhenError_thenServerError() {
         webSocketSession.onError(new RuntimeException("message"));
-        verify(webSocketSession, times(1)).close(CloseStatus.SERVER_ERROR);
+        verify(webSocketSession, times(1)).close(argThat(status -> status.getCode() == CloseStatus.SERVER_ERROR.getCode() && status.getReason().equals("message")));
     }
 
     @Test