How to declare Vault secrets containing equals sign as environment variables using Kubernetes?

I want to declare Vault secrets as environment variables while using Kubernetes with following configuration:

[...]
apiVersion: apps/v1
kind: Deployment
metadata:
  name: consumer-xyz
spec:
  replicas: 1
  selector:
    matchLabels:
      app: consumer-xyz
  template:
    metadata:
      annotations:
        vault.hashicorp.com/agent-init-first: "true"
        vault.hashicorp.com/agent-inject: "true"
        vault.hashicorp.com/agent-inject-secret-env: app-xyz-www/xyz/app
        vault.hashicorp.com/agent-inject-status: update
        vault.hashicorp.com/agent-inject-template-env: |
          {{- with secret "app-xyz-www/xyz/app" -}}
          {{- range $k, $v := .Data.data -}}
              export {{ $k }}='{{ $v }}'
          {{ end -}}
          {{- end -}}
        vault.hashicorp.com/agent-pre-populate-only: "true"
        vault.hashicorp.com/ca-cert: /vault/tls/ca-chain.crt
        vault.hashicorp.com/role: app-xyz-www
        vault.hashicorp.com/tls-secret: hashicorp-vault-ca-certificates
        vault.hashicorp.com/agent-run-as-user: "33"
        vault.hashicorp.com/agent-run-as-group: "33"
[...]

What happens is that if a value in Vault contains a = the line is cut at that point, so instead of say:

export ENV_1='https://www.example.com/endpoint?type=xml'

I get:

export ENV_1='https://www.example.com/endpoint?type

In fact the same happens if I write it directly:

        vault.hashicorp.com/agent-inject-template-env: |
          export ENV_1='https://www.example.com/endpoint?type=xml'

How can I export environment variables with = correctly?