Question: I'm attempting to add a custom header filter in my Dropwizard instance to check to see if the request's version is synced to the Dropwizard instance's version.

I see you can use `FilterBuilder` to add jetty `CrossOriginFilters`. However, I am having trouble figuring out how to set a custom filter.

Thanks

Answer: 
Via the Environment class.

<https://dropwizard.github.io/dropwizard/manual/core.html#environments> 

```
@Override
public void run(MyApplicationConfiguration configuration, Environment environment) {
    environment.servlets().addFilter("Custom-Filter-Name", new MyCustomFilter()).addMappingForUrlPatterns(EnumSet.allOf(DispatcherType.class), true, "/*");
}

```

You can choose which Dispatch types by changing `EnumSet.allOf(DispatcherType.class)`
This is how I got it to work using Dropwwizard 0.7.1 (APIs appear to have changed from other examples I found out there)

In run method of your application:

```
final FilterRegistration.Dynamic cors = environment.servlets().addFilter("crossOriginRequsts", CrossOriginFilter.class);
cors.addMappingForUrlPatterns(EnumSet.allOf(DispatcherType.class), true, "/*");

```

<https://gist.github.com/craigbeck/fb71818063175b9b4210>