I'm trying to use kubectl patch to add an extra annotation to my k8s nginx ingress.

Here's the ingress that I start with:

apiVersion: v1
items:
- apiVersion: extensions/v1beta1
  kind: Ingress
  metadata:
    annotations:
      field.cattle.io/publicEndpoints: '[{"stuff:false}]'
      kubernetes.io/ingress.class: nginx-external
    creationTimestamp: "2019-02-25T20:38:29Z"
    generation: 1

Here is my patch file that I'm applying ingress_annotation.yaml.

metadata:
  annotations:
    nginx.ingress.kubernetes.io/configuration-snippet: |
      proxy_set_header l5d-dst-override $service_name.$namespace.svc.cluster.local:80;
      proxy_hide_header l5d-remote-ip;
      proxy_hide_header l5d-server-id;

I apply this patch by running kubectl patch ingress kibana --patch "$(cat ingress_annotation.yaml)".

When I apply this it does add the annotation to the ingress looks like this when I run kubectl get ingress <my_ingress> -o yaml:

apiVersion: v1
items:
- apiVersion: extensions/v1beta1
  kind: Ingress
  metadata:
    annotations:
      field.cattle.io/publicEndpoints: '[{"Stuff:false}]'
      kubernetes.io/ingress.class: nginx-external
      nginx.ingress.kubernetes.io/configuration-snippet: |-
        proxy_set_header l5d-dst-override $service_name.$namespace.svc.cluster.local:80;
        proxy_hide_header l5d-remote-ip;
        proxy_hide_header l5d-server-id;
    creationTimestamp: "2019-02-25T20:38:29Z"
    generation: 1

Note the extra "-" character after nginx.ingress.kubernetes.io/configuration-snippet: |. I'm not sure where this character is coming from or what it's doing here. Can anyone shine some light on this for me, or how I can prevent this character from being added to my annotation?