ModifiedResponseBodyGatewayFilter only if the content-type condition of the response is met

[foameraserblue]

Is your feature request related to a problem? Please describe. I want to use ModifiedResponseBodyGatewayFilter only if the content-type condition of the response is met.

Describe the solution you'd like Provides a method to make it useful only when the content-type of the response is APPLICATION_JSON.

Describe alternatives you've considered I think it would be good to be able to add specific conditions to config and have those conditions judged in front of ModifiedServerHttpResponse.writeWith().

Additional context It's very difficult when an image file comes as a response.