Default server URL "/" is added automatically when parsing OpenAPI 3 spec

Description:
When I parse an OpenAPI 3.0 document using new OpenAPIV3Parser().readContents(...), a default server with URL "/" is automatically added if no servers are defined. This causes issues when the document is later used in Swagger UI or serialized with Json.mapper().writeValueAsString(...), as the unwanted "/" base path appears in the output.

Steps to Reproduce:

1. Use the swagger-parser library to read an OpenAPI spec that has no servers section.
2. Parse using:

OpenAPI openApi = new OpenAPIV3Parser().readContents(openApiString).getOpenAPI();
String openApiJson = Json.mapper().writeValueAsString(openApi);

3. Observe that the resulting openApiJson includes:

"servers": [
  {
    "url": "/"
  }
]

Expected Behavior:
If no servers are defined in the input OpenAPI spec, the parser should not add a default server URL, or there should be an option to disable it.

Actual Behavior:
A server with URL "/" is automatically inserted into the servers list.

Start at OpenAPIV3Parser().readContents(...) and reproduce the issue with an OpenAPI 3 document that has no servers section. Trace where the default server is added, then verify serialization with Json.mapper().writeValueAsString(...); done means parsing no longer emits a "/" server when the input omits servers.