Code generated by NSwag.ApiDescription.Client generates incorrect URLs

[ebarnard]

Describe the bug

When updating to NSwag v14 from v13, I've found that segmented URLs where the last segment is optional are generated incorrectly.

var urlBuilder_ = new System.Text.StringBuilder();

// Operation Path: "views/searchinstruments/{type}/{query}"
urlBuilder_.Append("views/searchinstruments/");
urlBuilder_.Append(System.Uri.EscapeDataString(ConvertToString(type, System.Globalization.CultureInfo.InvariantCulture)));
urlBuilder_.Append('/');
if (query != null)
{
    urlBuilder_.Append(System.Uri.EscapeDataString(ConvertToString(query, System.Globalization.CultureInfo.InvariantCulture)));
}
else
    if (urlBuilder_.Length > 0) urlBuilder_.Length--;
urlBuilder_.Append("{query}");

PrepareRequest(client_, request_, urlBuilder_);

Version used

v14.0.0 and v14.2.0

To Reproduce

No small reproducer yet, but this is a snippet of the OpenAPI V3 JSON from which the code above is generated:

"/views/searchinstruments/{type}/{query}": {
  "get": {
    "tags": [
      "Searches"
    ],
    "operationId": "GetSearchInstrumentsEndpoint_Get",
    "parameters": [
      {
        "name": "x-actor-id",
        "in": "header",
        "required": true,
        "schema": {
          "type": "string"
        },
        "examples": {
          "No Netwealth data": {
            "value": "5df23838-73eb-41e8-893f-b6cfd019ade3"
          }
        }
      },
      {
        "name": "type",
        "in": "path",
        "required": true,
        "schema": {
          "type": "string"
        },
        "examples": {
          "All": {
            "value": "All"
          },
          "Cash": {
            "value": "Cash"
          },
          "Common Stock": {
            "value": "Common Stock"
          },
          "ETF": {
            "value": "ETF"
          },
          "Fund": {
            "value": "Fund"
          },
          "Investment Trust": {
            "value": "Investment Trust"
          }
        }
      },
      {
        "name": "query",
        "in": "path",
        "schema": {
          "type": "string"
        }
      }
    ],
    "responses": {
      "200": {
        "description": "A success response",
        "content": {
          "application/json": {
            "schema": {
              "$ref": "#/components/schemas/getSearchInstrumentsEndpointResponse"
            },
            "examples": {
              "Single Instrument": {
                "value": "{\"instruments\":[{\"name\":\"Apple\",\"code\":\"AAPL\",\"currency\":\"USD\",\"isGBX\":false,\"isin\":\"US12345\",\"assetClassType\":\"Common Stock\",\"exchange\":\"US\",\"ticker\":\"AAPL\",\"isStatic\":false}],\"totalFoundInstruments\":1}"
              }
            }
          }
        }
      },
      "400": {
        "description": "A bad request response"
      }
    },
    "security": [
      {
        "function_key": [ ]
      }
    ]
  }
},

Expected behavior

The URL does not contain the string "{query}" at the end.