Don't prepend slashes to baseUrl if baseUrl already begins with a slash

Author: alexweav

modules/swagger-parser-v2-converter/src/main/java/io/swagger/v3/parser/converter/SwaggerConverter.java

@@ -420,7 +420,7 @@ private List<Server> convert(List<Scheme> schemes, String host, String basePath)
                 servers.add(server);
             }
         } else {
-            if (!"/".equals(baseUrl)) {
+            if (!StringUtils.startsWith(baseUrl, "/") && !"/".equals(baseUrl)) {
                 baseUrl = "//" + baseUrl;
             }
             Server server = new Server();